History of Psychology Essay - 2242 Words

Dating back 65000 years, Aborigines have had the longest continuous culture. The Aborigines believed and lived in the ‘Dreamtime’. The ‘dreamtime’ refers to the time when land and humans were created, and when ancestors and spirits came to earth and created everything. Every tribe had their own dreamtime and was passed down through storytelling. The Aborigines connection was either through the Wandjina or the rainbow serpent depending on the tribe. For the Aboriginals the world is sacred and has to be honoured. For the Aborigines everything is related to everything else therefore man was related to fellow man, animals, stars and the cosmos (Bowles, 2010). Even the men and women were equal because they were equally divine. The Aborigines†¦show more content†¦For the Aborigines everything has meaning and is spiritual unlike our secular society today whereby only 2% of the Britain population actually attend church. There is no gods or the spiritual wor ld anymore. It’s all about reason and rationality. The society today tends to believe more in science than intuition. Moving on to see how the psyche was imagined through works of Hesiod and Homer in the 7th Century B.C. Hesiod tells us that the world parents were Gaia and Uranus (Bowles, 2010). According to the module workbook Uranus was a tyrannical god and feared that his children would usurp his power and therefore he hid them in the underworld. However, one of his son Cronos came back when he got older and castrated his father. He feared the same thing like his father did and so he swallowed his children. His wife managed to save one of the children namely Zeus and sent him to be brought up by the shepherds. As we all know history repeats itself, Zeus came back and gave his father a potion to vomit the rest of the children and then castrated him. He also managed to release his father’s brothers. Psychologically if a father eats his children, it’s a metaphor for a father who tries to take over his childrens’ lives i.e no space or freedom. Zeus then shared the world with his brothers and lived in Mount Olympus with his wife Hera and his children by Hera and as well as other women. Mount Olympus was believed to be the place where all the gods and goddesses lived. In theShow MoreRelatedHistory of Psychology753 Words   |  4 PagesHistory of Psychology History of Psychology Paper Shirley L Nieves October 21, 2013 PSY/310 Prof. Kelle Daniels The roots of psychology date back to Egypt and the Egyptian mystery system. Psychology has evolved from philosophy, medicine, theology, and science. Psychology evolved out of coalescence of natural science, and also the branch of philosophy which is known as epistemology, which is also known in the theory of knowledgeRead MoreHistory of Psychology852 Words   |  4 PagesWhat is Psychology? Psychology is said to be the scientific study of behavior and mental processes. The study of human behavior, development, and learning; and also seeks to understand and explain thought, emotion, and behavior. Today the question we are doing falls under the History of Psychology. It deals with the earlier schools (Structuralism and Functionalism) and compares them with the most recent schools of psychology (Gestalt psychology, Psychoanalysis and CognitiveRead MoreThe History of Psychology2719 Words   |  11 PagesIntroduction: The History of Psychology Philosophical Background Psychology has no definite, absolute beginning, but there is speculation that early humans were curious about human nature. Serious study of the human psyche began in ancient times, with ancient philosophers began to record their findings and thoughts about behavior and the nature of the human mind. The name ‘psychology is from the two Greek roots, psyche and logos, which mean mind and study, respectively. Psychological thoughtRead MoreHistory of Modern Psychology836 Words   |  4 PagesA History of Modern Psychology Franklyn Rivas UOPX History and Systems in Psychology 310 Lillian Fillpot May 03, 2011 A History of Modern Psychology Before psychology officially became a science, many great intellectuals of previous centuries had contributed to the philosophy behind psychology. This philosophy can be trace back to the times of the Greeks, middle ages, and the renaissance period. However, the link between philosophy and modern psychology became possible in the late 18thRead MoreEssay on The History of Psychology1423 Words   |  6 PagesThe History of Psychology In order to discuss Psychologys history, it is important to understand that psychology still does not have one unifying approach unlike the natural sciences; even the definition of Psychology and what it truly means is still undecided. However I shall attempt to review chronologically its philosophical origins, include how the science of Physics and Biology were placedRead MoreHistory of Psychology Paper1294 Words   |  6 PagesHistory of Psychology Paper Jessica PSY/310 May 3, 2010 CERTIFICATE OF ORIGINALITY: I certify that the attached paper, which was produced for the class identified above, is my original work and has not previously been submitted by me or by anyone else for any class. I further declare that I have cited all sources from which I used language, ideas and information, whether quoted verbatim or paraphrased, and that any and all assistance of any kind, which I received while producing this paperRead MoreHistory of Cognitive Psychology1666 Words   |  7 PagesAbstract An analysis of the history of cognitive psychology. Including key ideas, contributors, trends, etc. History of Cognitive Psychology According to G. Miller of Princeton University, cognitive psychology  is an approach to psychology that emphasizes internal mental processes. So, â€Å"since the beginning of experimental psychology in the nineteenth century, there had been interest in the study of higher mental processes. But something discontinuous happened in the late 1950s, something soRead MoreHistory And Systems Of Psychology1795 Words   |  8 Pages History and Systems of Psychology is a course requirement offered to Psychology majors and minors. This course is used to provide majors and minors with the foundation and the evolution of the field of psychology. Within this class, many scholars of discussed. Two scholars that stood out to me in this course would be John Watson and Max Wertheimer. These two particular scholars are responsible for two of the most influential and famous schools of thought, behaviorism and Gestalt psychology. TheseRead MoreThe History Of Social Psychology2266 Words   |  10 PagesThe history of social psychology goes far back in time. â€Å"Aristotle believed that humans were naturally sociable, a necessity which allows us to live together.† (McLeod) Plato was also another influencer in social psychology by saying that â€Å"the state controlled by the individual and encouraged social responsibility through social context. (McLeod) Social psychology is the section of psychology that studies i ndividuals in a social environment. It studies how people think and how they feel, and whyRead MoreHistory And Systems Of Psychology3029 Words   |  13 Pages SOUTHWESTERN ASSEMBLIES OF GOD UNIVERSITY History and Systems of Psychology Psy 4113.00 Instructor: Dr. John Savell History and Systems of Psychology School of Thought Research Paper STUDENT DATA: Name Lauren Frost E-mail: laurenbfrost@lionmail.sagu.edu Phone: (318)372-3825 Semester: Fall 2014 Date: October 8, 2014 Psychoanalysis Psychoanalysis is the belief that we are blissfully unaware of circumstances that dictate ones emotions and behavior. Psychoanalytic school of thought looks

A Raisin In The Sun Character Analysis - 1592 Words

Money and acquisitiveness have always had the ability to turn people into someone they are not. Greed can tear apart families and friendships when a person neglects others for their own benefit. This is depicted perfectly in Lorraine Hansberry’s play A Raisin in the Sun which follows the lives of the Youngers, an African-American family living in 1950’s South Side Chicago. The focus is on a man named Walter Younger, who has the difficult decision of choosing between his personal dream and the progression of his family, which would require him to give up his dream. Walter’s personal dream is to open up a liquor store with his buddies, but in order for his family to make real progress in the world and escape the hole that is poverty, they†¦show more content†¦In this scene, there is a profound statement made about Walter’s behavior. He is certainly prideful, but maybe his pride isnt in the right place. He seems to have more pride about money than an ything else, including his own family. In the opening scenes of the play, Walter makes it clear that to him, money matters more than most things, if not all. This is quite odd, with the fact being that he has very little of it. He treats his wife poorly, argues with her, and deliberately defies what she is doing to prove that he’s got money. He doesnt want Travis to feel like they have money problems, even though they very much do. Ultimately, up to this point, Walter has portrayed himself as a self-centered person who cares more about his own pride and how hes perceived than his family’s well being. If he continues with this careless behavior, his family may never progress. Much later, Walter has a dramatic shift in his character, with him now having a false sense of pride instead of a misplaced sense of pride. When he finally receives what he has always wanted, wealth, it changes the way he acts. However, it does not change him for the better, or allow him to improve his family’s situation. When Mama gives him the large sum of money from Walter Sr’s insurance check, she sincerely tells him, â€Å"I ain’t never stop trusting you. Like IShow MoreRelatedCharacter Analysis Of A Raisin Of The Sun Essay845 Words   |  4 PagesWriting Assignment 4: Character Analysis of â€Å"A Raisin in the Sun† The male protagonist of this story is Walter Lee Younger, an African American, who plays the roles of a son, husband, father, and brother. The story is set in a Chicago Southside apartment, â€Å"sometime between World War II and the present [1959]† (Hansberry 919). Walter is physically described as â€Å"a lean, intense young man in his middle thirties, inclined to quick nervous movements and erratic speech habits—and always in his voiceRead MoreA Raisin In The Sun Character Analysis1322 Words   |  6 PagesIn the play â€Å"A Raisin in the Sun† written by Lorraine Hansberry, she is able to take us to place to see what it was like for an African American family to survive in the mid-twentieth century. The play details how the main characters are going through an evolving social and economic position, as well as the evolving gender roles. Hansberry uses the characterization of Beneatha, Ruth, and Walter in order to show the expectations and assigned gender roles for the characters in the story. In shortRead MoreA Raisin In The Sun Character Analysis902 Words   |  4 PagesGordon: Segregation vs. Southern Pride Lorraine Hansberry’s â€Å"A Raisin in the Sun† touches on many issues African Americans faced in the early to mid-twentieth century. One can analyze Hansberry’s â€Å"A Raisin in the Sun† from many angles, and come away with different meanings. While Michelle Gordon focuses more on segregation and housing discrimination that plagued African Americans on Chicago’s Southside in Hansberry’s â€Å"A Raisin in the Sun†, William Murray emphasizes on Southern Pride and heritage. ThisRead MoreA Raisin In The Sun Character Analysis917 Words   |  4 PagesIn the play A Raisin in the Sun by Lorraine Hansberry the Younger family faces many conflicts. This is mainly because they are living in Chicago in the 1950’s. This was a time where many African Americans were discriminated, which caused the family to have many issues with money, jobs, and family. Two characters from the pay that help influence the plot would be Mama and Ruth. This i s because of the roles they play, their conflicts, and their actions towards other character. Without the roles ofRead MoreA Raisin In The Sun Character Analysis1026 Words   |  5 PagesIn A Raisin in the Sun by Lorraine Hansberry, one of the featured characters is outgoing and ambitious Beneatha Younger, sister of Walter and daughter of Mama. Beneatha, commonly referred to as Bennie by her family, is an aspiring doctor and currently in medical school. In addition to these desires, she also acquires relationships with Asagai and George Murchinson, two prominent male characters, throughout the course of the play. Although her career choice and relations with these men are completelyRead MoreCharacter Analysis Of Beneatha In A Raisin In The Sun1487 Words   |  6 PagesCharacter Analysis â€Å" A Raisin in the Sun† is a play written by Lorraine Hansberry about the life of an African American family during the era of segregation. The play starts off with the Younger family receiving a 10,000 dollar check from Mr. Younger’s insurance policy. The family argues over what they are going to do with it. Mama wants to buy a house with it, Walter wants to invest in a liquor store, and Beneatha wants to use the money to go to medical school. The contrast of the characters’ personalitiesRead MoreA Raisin In The Sun Character Analysis1052 Words   |  5 PagesName Instructor Name Class Date Walter Lee Younger in A Raisin in the Sun Lorraine Hansberry’s play, A Raisin in the Sun, tells the story of the Younger family, an African-American family living in poverty in 1950s Chicago. The family patriarch, Walter, is a limousine driver struggling to make ends meet and desperate to find a way to propel his family toward wealth. With his father’s death comes an insurance check for $10,000 and each member of the family has different ideas on what to do withRead MoreA Raisin In The Sun Character Analysis1322 Words   |  6 Pages Lorraine Hansberry’s play, A Raisin in the Sun, depicts the lives of the Younger family, an African American family living in the Southside of Chicago during the 1950s. The play takes place in their cramped apartment offering the reader insight into the arguments, discussions, and conversations that take place between the characters. In one scene, Hansberry specifically offers the reader a conversation between Asagai, an influential companion, and Beneatha to show us how disparate the Younger siblingsRead MoreCharacter Analysis Of Raisin In The Sun798 Words   |  4 PagesIn the play a Raisin in the Sun, Walter Lee Younger is an African American man who portrays the role of a father, son, and husband. He has a dream to invest the incoming inherence into something that may help his family in the future. Once this idea comes to him it takes over his mind, and he cannot stop thinking about it. It acts as though its a drug, he addicted to talking about it. Also, when it is broug ht up in a conversation and someone disagrees he become very defensive. In addition, he isRead MoreCharacter Analysis Of A Raisin In The Sun1299 Words   |  6 Pagessoul longs for the satisfaction of meeting a goal? The obstacles along the way may cause one trouble, but one still strives for that personal satisfaction of knowing something grand was accomplished. A Raisin In The Sun, written by Lorraine Hansberry, gives off many aspects of the story’s characters wanting the reward of being able to say, â€Å"I did it†. Beneatha Younger, a passionate, strong-willed woman will do whatever it takes to pursue her dream of attending medical school. Along the way of wanting

Physical Properties and Reactions free essay sample

These pages explain the relationship between the physical properties of the oxides of Period 3 elements (sodium to chlorine) and their structures. Argon is obviously omitted because it doesnt form an oxide. A quick summary of the trends The oxides The oxides well be looking at are: |Na2O |MgO |Al2O3 |SiO2 |P4O10 |SO3 |Cl2O7 | | | | | |P4O6 |SO2 |Cl2O | Those oxides in the top row are known as the highest oxides of the various elements. These are the oxides where the Period 3 elements are in their highest oxidation states. In these oxides, all the outer electrons in the Period 3 element are being involved in the bonding from just the one with sodium, to all seven of chlorines outer electrons. The structures The trend in structure is from the metallic oxides containing giant structures of ions on the left of the period via a giant covalent oxide (silicon dioxide) in the middle to molecular oxides on the right. Melting and boiling points The giant structures (the metal oxides and silicon dioxide) will have high melting and boiling points because a lot of energy is needed to break the strong bonds (ionic or covalent) operating in three dimensions. The oxides of phosphorus, sulphur and chlorine consist of individual molecules some small and simple; others polymeric. The attractive forces between these molecules will be van der Waals dispersion and dipole-dipole interactions. These vary in size depending on the size, shape and polarity of the various molecules but will always be much weaker than the ionic or covalent bonds you need to break in a giant structure. These oxides tend to be gases, liquids or low melting point solids. Electrical conductivity None of these oxides has any free or mobile electrons. That means that none of them will conduct electricity when they are solid. The ionic oxides can, however, undergo electrolysis when they are molten. They can conduct electricity because of the movement of the ions towards the electrodes and the discharge of the ions when they get there. The metallic oxides The structures Sodium, magnesium and aluminum oxides consist of giant structures containing metal ions and oxide ions. Melting and boiling points There are strong attractions between the ions in each of these oxides and these attractions need a lot of heat energy to break. These oxides therefore have high melting and boiling points. Electrical conductivity None of these conducts electricity in the solid state, but electrolysis is possible if they are molten. They conduct electricity because of the movement and discharge of the ions present. The only important example of this is in the electrolysis of aluminum oxide in the manufacture of aluminum. Whether you can electrolyze molten sodium oxide depends, of course, on whether it actually melts instead of subliming or decomposing under ordinary circumstances. If it sublimes, you wont get any liquid to electrolyze! Magnesium and aluminum oxides have melting points far too high to be able to electrolyze them in a simple lab. Silicon dioxide (silicon(IV) oxide) The structure The electronegativity of the elements increases as you go across the period, and by the time you get to silicon, there isnt enough electronegativity difference between the silicon and the oxygen to form an ionic bond. Silicon dioxide is a giant covalent structure. There are three different crystal forms of silicon dioxide. The easiest one to remember and draw is based on the diamond structure. Melting and boiling points Silicon dioxide has a high melting point varying depending on what the particular structure is (remember that the structure given is only one of three possible structures), but they are all around 1700 °C. Very strong silicon-oxygen covalent bonds have to be broken throughout the structure before melting occurs. Silicon dioxide boils at 2230 °C. Because you are talking about a different form of bonding, it doesnt make sense to try to compare these values directly with the metallic oxides. What you can safely say is that because the metallic oxides and silicon dioxide have giant structures, the melting and boiling points are all high. Electrical conductivity Silicon dioxide doesnt have any mobile electrons or ions so it doesnt conduct electricity either as a solid or a liquid. The molecular oxides Phosphorus, sulphur and chlorine all form oxides which consist of molecules. Some of these molecules are fairly simple others are polymeric. We are just going to look at some of the simple ones. Melting and boiling points of these oxides will be much lower than those of the metal oxides or silicon dioxide. The intermolecular forces holding one molecule to its neighbors’ will be van der Waals dispersion forces or dipole-dipole interactions. The strength of these will vary depending on the size of the molecules. None of these oxides conducts electricity either as solids or as liquids. None of them contains ions or free electrons. The phosphorus oxides Phosphorus has two common oxides, phosphorus (III) oxide, P4O6, and phosphorus (V) oxide, P4O10. Phosphorus (III) oxide (tetraphosphorus hexoxide) Phosphorus (III) oxide is a white solid, melting at 24 °C and boiling at 173 °C. The phosphorus is using only three of its outer electrons (the 3 unpaired p electrons) to form bonds with the oxygens. Phosphorus (V) oxide (tetraphosphorus decoxide) Phosphorus (V) oxide is also a white solid, subliming (turning straight from solid to vapour) at 300 °C. In this case, the phosphorus uses all five of its outer electrons in the bonding. Solid phosphorus(V) oxide exists in several different forms some of them polymeric. We are going to concentrate on a simple molecular form, and this is also present in the vapour. This is most easily drawn starting from P4O6. The other four oxygens are attached to the four phosphorus atoms via double bonds. [pic] The sulphur oxides Sulphur has two common oxides, sulphur dioxide (sulphur (IV) oxide), SO2, and sulphur trioxide (sulphur (VI) oxide), SO3. Sulphur dioxide Sulphur dioxide is a colourless gas at room temperature with an easily recognized choking smell. It consists of simple SO2 molecules. [pic] The sulphur uses 4 of its outer electrons to form the double bonds with the oxygen, leaving the other two as a lone pair on the sulphur. The bent shape of SO2 is due to this lone pair. Sulphur trioxide Pure sulphur trioxide is a white solid with a low melting and boiling point. It reacts very rapidly with water vapour in the air to form sulphuric acid. That means that if you make some in the lab, you tend to see it as a white sludge which fumes dramatically in moist air (forming a fog of sulphuric acid droplets). Gaseous sulphur trioxide consists of simple SO3 molecules in which all six of the sulphurs outer electrons are involved in the bonding. [pic] There are various forms of solid sulphur trioxide. The simplest one is a trimer, S3O9, where three SO3 molecules are joined up and arranged in a ring. The fact that the simple molecules join up in this way to make bigger structures is what makes the sulphur trioxide a solid rather than a gas. The chlorine oxides Chlorine forms several oxides. Here we are just looking at two of them – chlorine (I) oxide (dichlorine monoxide), Cl2O, and chlorine (VII) oxide (dichlorine heptoxide), Cl2O7. Chlorine (I) oxide (dichlorine monoxide) Chlorine (I) oxide is a yellowish-red gas at room temperature. It consists of simple small molecules. [pic] Theres nothing in the least surprising about this molecule and its physical properties are just what you would expect for a molecule this size. Chlorine (VII) oxide (dichlorine heptoxide) In chlorine (VII) oxide, the chlorine uses all of its seven outer electrons in bonds with oxygen. This produces a much bigger molecule, and so you would expect its melting point and boiling point to be higher than chlorine (I) oxide. Chlorine (VII) oxide is a colourless oily liquid at room temperature. The diagram has been drawn as a standard structural formula for simplicity. In fact, the shape is tetrahedral around both chlorines, and V-shaped around the central oxygen. [pic] PROPERTIES OF THE PERIOD 3 CHLORIDES This page looks at the structures of the chlorides of the Period 3 elements (sodium to sulphur*), their physical properties and their reactions with water. Chlorine and argon are omitted chlorine because it is meaningless to talk about chlorine chloride, and argon because it doesnt form a chloride. A quick summary of the trends The chlorides The chlorides well be looking at are: |NaCl |MgCl2 |AlCl3 |SiCl4 |PCl5 |S2Cl2 | | | | | |PCl3 | | As you will see later, aluminum chloride exists in some circumstances as a dimer, Al2Cl6. The structures Sodium chloride and magnesium chloride are ionic and consist of giant ionic lattices at room temperature Aluminum chloride and phosphorus (V) chloride are tricky! They change their structure from ionic to covalent when the solid turns to a liquid or vapour. There is much more about this later on this page. The others are simple covalent molecules. Melting and boiling points Sodium and magnesium chlorides are solids with high melting and boiling points because of the large amount of heat (energy) which is needed to break the strong ionic attractions. The rest are liquids or low melting point solids. Leaving aside the aluminum chloride and phosphorus (V) chloride cases where the situation is quite complicated, the attractions in the others will be much weaker intermolecular forces such as van der Waals dispersion forces. These vary depending on the size and shape of the molecule, but will always be far weaker than ionic bonds. Electrical conductivity Sodium and magnesium chlorides are ionic and so will undergo electrolysis when they are molten. Electricity is carried by the movement of the ions and their discharge at the electrodes. In the aluminum chloride and phosphorus (V) chloride cases, the solid doesnt conduct electricity because the ions arent free to move. In the liquid (where it exists both of these sublime at ordinary pressures), they have converted into a covalent form, and so dont conduct either. The rest of the chlorides dont conduct electricity either solid or molten because they dont have any ions or any mobile electrons. Reactions with water As an approximation, the simple ionic chlorides (sodium and magnesium chloride) just dissolve in water. The other chlorides all react with water in a variety of ways described below for each individual chloride. The reaction with water is known as hydrolysis. The Individual Chlorides Sodium chloride, NaCl Sodium chloride is a simple ionic compound consisting of a giant array of sodium and chloride ions. A small representative bit of a sodium chloride lattice looks like this: [pic] This is normally drawn in an exploded form as: [pic] The strong attractions between the positive and negative ions need a lot of heat energy to break, and so sodium chloride has high melting and boiling points. It doesnt conduct electricity in the solid state because it hasnt any mobile electrons and the ions arent free to move. However, when it melts it undergoes electrolysis. Sodium chloride simply dissolves in water to give a neutral solution. Magnesium chloride, MgCl2 Magnesium chloride is also ionic, but with a more complicated arrangement of the ions to allow for having twice as many chloride ions as magnesium ions. Again, lots of heat energy is needed to overcome the attractions between the ions, and so the melting and boiling points are again high. Solid magnesium chloride is a non-conductor of electricity because the ions arent free to move. However, it undergoes electrolysis when the ions become free on melting. Magnesium chloride dissolves in water to give a faintly acidic solution (pH = approximately 6). When magnesium ions are broken off the solid lattice and go into solution, there is enough attraction between the 2+ ions and the water molecules to get co-ordinate (dative covalent) bonds formed between the magnesium ions and lone pairs on surrounding water molecules. Hexaaquamagnesium ions are formed, [Mg(H2O)6]2+. [pic][pic] Ions of this sort are acidic the degree of acidity depending on how much the electrons in the water molecules are pulled towards the metal at the centre of the ion. The hydrogens are made more positive than they would otherwise be, and more easily pulled off by a base. In the magnesium case, the amount of distortion is quite small, and only a small proportion of the hydrogen atoms are removed by a base in this case, by water molecules in the solution. [pic][pic] The presence of the hydronium ions in the solution causes it to be acidic. The fact that there arent many of them formed (the position of equilibrium lies well to the left), means that the solution is only weakly acidic. You may also find the last equation in a simplified form: [pic][pic] Hydrogen ions in solution are hydronium ions. If you use this form, it is essential to include the state symbols. Aluminum chloride, AlCl3 Electronegativity increases as you go across the period and, by the time you get to aluminum; there isnt enough electronegativity difference between aluminum and chlorine for there to be a simple ionic bond. Aluminum chloride is complicated by the way its structure changes as temperature increases. At room temperature, the aluminum in aluminum chloride is 6-coordinated. That means that each aluminum is surrounded by 6 chlorines. The structure is an ionic lattice although with a lot of covalent character. At ordinary atmospheric pressure, aluminum chloride sublimes (turns straight from solid to vapour) at about 180 °C. If the pressure is raised to just over 2 atmospheres, it melts instead at a temperature of 192 °C. Both of these temperatures, of course, are completely wrong for an ionic compound they are much too low. They suggest comparatively weak attractions between molecules not strong attractions between ions. The coordination of the aluminum changes at these temperatures. It becomes 4-coordinated each aluminum now being surrounded by 4 chlorines rather than 6. What happens is that the original lattice has converted into Al2Cl6 molecules. [pic] This conversion means, of course, that you have completely lost any ionic character which is why the aluminum chloride vaporizes or melts (depending on the pressure). There is an equilibrium between these dimers and simple AlCl3 molecules. As the temperature increases further, the position of equilibrium shifts more and more to the right. [pic][pic] Summary †¢ At room temperature, solid aluminum chloride has an ionic lattice with a lot of covalent character. At temperatures around 180 190 °C (depending on the pressure), aluminum chloride coverts to a molecular form, Al2Cl6. This causes it to melt or vaporize because there are now only comparatively weak intermolecular attractions. †¢ As the temperature increases a bit more, it increasingly breaks up into simple AlCl3 molecules. Solid aluminum chloride doesnt conduct electricity at room temperature because the ions arent free to move. Mo lten aluminum chloride (only possible at increased pressures) doesnt conduct electricity because there arent any ions any more. The aluminum chloride reacts with the water rather than just dissolving in it. In the first instance, hexaaquaaluminum ions are formed together with chloride ions. [pic][pic] You will see that this is very similar to the magnesium chloride equation given above the only real difference is the charge on the ion. That extra charge pulls electrons from the water molecules quite strongly towards the aluminum. That makes the hydrogens more positive and so easier to remove from the ion. In other words, this ion is much more acidic than in the corresponding magnesium case. These equilibria (whichever you choose to write) lie further to the right, and so the solution formed is more acidic there are more hydroxonium ions in it. [pic][pic] or, more simply: [pic][pic] Silicon tetrachloride, SiCl4 Silicon tetrachloride is a simple no-messing-about covalent chloride. There isnt enough electronegativity difference between the silicon and the chlorine for the two to form ionic bonds. Silicon tetrachloride is a colourless liquid at room temperature which fumes in moist air. The only attractions between the molecules are van der Waals dispersion forces. It doesnt conduct electricity because of the lack of ions or mobile electrons. It fumes in moist air because it reacts with water in the air to produce hydrogen chloride. If you add water to silicon tetrachloride, there is a violent reaction to produce silicon dioxide and fumes of hydrogen chloride. In a large excess of water, the hydrogen chloride will, of course, dissolve to give a strongly acidic solution containing hydrochloric acid. [pic] The phosphorus chlorides There are two phosphorus chlorides – phosphorus (III) chloride, PCl3, and phosphorus (V) chloride, PCl5. Phosphorus (III) chloride (phosphorus trichloride), PCl3 This is another simple covalent chloride again a fuming liquid at room temperature. It is a liquid because there are only van der Waals dispersion forces and dipole-dipole attractions between the molecules. It doesnt conduct electricity because of the lack of ions or mobile electrons. Phosphorus (III) chloride reacts violently with water. You get phosphorous acid, H3PO3, and fumes of hydrogen chloride (or a solution containing hydrochloric acid if lots of water is used). [pic][pic] Phosphorus (V) chloride (phosphorus pentachloride), PCl5 Unfortunately, phosphorus (V) chloride is structurally more complicated. Phosphorus (V) chloride is a white solid which sublimes at 163 °C. The higher the temperature goes above that, the more the phosphorus (V) chloride dissociates (splits up reversibly) to give phosphorus (III) chloride and chlorine. [pic][pic] Solid phosphorus (V) chloride contains ions which is why it is a solid at room temperature. The formation of the ions involves two molecules of PCl5. A chloride ion transfers from one of the original molecules to the other, leaving a positive ion, [PCl4]+, and a negative ion, [PCl6]-. At 163 °C, the phosphorus (V) chloride converts to a simple molecular form containing PCl5 molecules. Because there are only van der Waals dispersion forces between these, it then vaporizes. Solid phosphorus (V) chloride doesnt conduct electricity because the ions arent free to move. Phosphorus (V) chloride has a violent reaction with water producing fumes of hydrogen chloride. As with the other covalent chlorides, if there is enough water present, these will dissolve to give a solution containing hydrochloric acid. The overall equation in boiling water is: pic] *Disulphur dichloride, S2Cl2* Disulphur dichloride is a simple covalent liquid orange and smelly! The shape is surprisingly difficult to draw convincingly! The atoms are all joined up in a line but twisted: [pic] The reason for drawing the shape is to give a hint about what sort of intermolecular attractions are possible. There is no plane of symmetry in the molecule and that means that it will have an overall permanent d ipole. The liquid will have van der Waals dispersion forces and dipole-dipole attractions. There are no ions in disulphur dichloride and no mobile electrons so it never conducts electricity. Disulphur dichloride reacts slowly with water to produce a complex mixture of things including hydrochloric acid, sulphur, hydrogen sulphide and various sulphur-containing acids and anions (negative ions). There is no way that you can write a single equation for this and one would never be expected in an exam. Summary 1. Physical properties of oxides: The physical properties of these oxides depend on the type of bonding. Na2O, Al2O3 and MgO are ionic oxides and hence have a high melting point. MgO and Al2O3 have a higher melting point than Na2O since the charges are higher, resulting in a stronger attraction between the ions. SiO2 has a giant covalent structure and hence a high melting point. There are strong covalent bonds between all the atoms and thus lots of energy is required to break them. P4O10 and SO3 are molecular covalent and so only intermolecular forces exist between the molecules. The melting points are thus much lower. P4O10 is a much bigger molecule than SO3 and so has a much higher melting point, as the van der Waal’s forces are stronger. Element |Na |Mg |Al |Si |P |S | |Formulae of oxide |Na2O |MgO |Al2O3 |SiO2 |P4O10 |SO3 | |Structure of oxide |Ionic |Ionic |Mostly ionic |Giant covalent |Molecular covalent|Molecular covalent | |Melting point of oxide / °C |1275 |2852 |2072 |1703 |300 |-10 | 2. Acid-base character of oxides.