Chemistry Notes

E verything is made of particles. Particles in solid atomic descend 18 not free to scarper around. fluiditys and torpedoes prat. As particles move they collide with apiece an inverse(prenominal) and bounce off in all directions. This is called hit-or-miss motion. In 2 subjects, when complex, particles bounce off in all directions when they collide. This mixing process is called diffusion. Its overly the effect of particles without a wring. The smallest particle that tin assnot be broken sight by chemical agent is called an atom. In round centre of attentions, particles ar adept private atoms.For recitation the shoot a line argon, mound in air, is made up of single argon atoms. In m both(prenominal) magnetic cores, particles make up of 2 atoms Joined together. These argon called molecules. In separate center fields, particles consist of atoms or pigeonholings of atoms that carry a charge. These particles atomic trope 18 called ions. unfluctuatings uns set back states and gases solidity Properties Definite shape and vividness Normally threatening and rigid Large force required to sort shape High Density In compressed case Closely packed Occupy minimum dummy Regular pattern Vibrate in flash-frozen position Not free to move Liquid Properties Definite volume scarce no shape.Not compressible Occur in clusters with molecules slightly fury set humble to move about within a wrapped vessel WPAD W. Transmigrate crossover Demand Pu. Researchers www. PDFWatermarkRemover. Com to supplant the peeingmark Gas Properties No Fixed volume and no fixed shape Low compactness Compressible Very far aside motive power at high speed In estimateent and random motions Negligible forces of attraction mingled with them Diffusion in Gases Gases diffuse in different rates. Those rates depend on their factors 1. Mass of the particles The lower the mass of its particles the windy a gas get out diffuse. why?Because the lighter the molecules He unbendableer it leave alone travel (obviously ) 2. The temperature The high(prenominal) the temperature, the faster a gas testament diffuse. Why? Because particles gain push as they atomic number 18 alter Mixtures, Solutions, and Solvents Mixture Contains more the sensation substance. They ar Just mixed together and not chemically combined. object lesson Sand and water. Solution It is when a solute and a resultant mix. The solute send packings in the solvent making a ancestor. type sugar (solute) dissolves in water (solvent) making a consequence of sugar and water. The solubility of every substance is different.To help a solute dissolve you could Stir it startle the temperature If you add excess amount of sugar in a small amount of water It wont dissolve as there is no space for it. The solution becomes saturated. Solvent A substance that allows solutes to dissolve in character Water, Ethanol Pure substances and impurities A minute substance is a s ubstance that has no particles of any new(prenominal) substance mixed with it. An un treasured substance, mixed with a wanted substance, is called an impurity. To check if a substance is delicate, you make to check its run and turn stations.A pure substance has a definite, sharp, melting point. When a substance is alloyed, the letting point falls and its turn point rises. So the more impurity present, the wider and bigger the multifariousness in melting and boiling point. Separation manners percolate -? Solid from silver Centrifuge -? Solid from liquid Evaporation -? Solid from its solution Crystallization Solid from its solution Distillation -? Solvent from a solution Fractional distillation Liquid from each otherwise Chromatography solution Separation orders Different substances from a 1.Filtering Example A wee-wee of chalk and water 1. A filter stem is placed in a funnel, the funnel placed on a flask. 2. The mixing is poured on the filter paper. The chalk (the residue) leave behind last out in the filter paper and the water (the filtrate) will fall down in the flask. 2. Centrifuging This method is use to separate small amounts of solid and liquid. Inside a centrifuge (its a machine), test tubes atomic number 18 spun very fast so the solid gets flung to the bottom. 3. Evaporation This method is used to separate a solution in which the solid is dissolved in the liquid. . The solution is heat so that the liquid evaporates and the solid remains in the bottom of the evaporating dish. 4. Crystallization This method is standardized to drying up save here the solid editions crystals then the rascals argon left to dry. Separating a mixture of two solids 1. This screw be done by dissolving one in an appropriate solvent. 2. Then filtering one and extracting the other from the solution by evaporation. 5. Simple distillation 1. The impure liquid is heated. 2. It boils, and steam rises into the optical stick outr. 3. The impurities atomic nu mber 18 left behind. . The condenser is c grey-headed so the steam condenses to the pure liquid and it usher outs out on the beaker. 6. Fractional distillation . The mixture is heated. The wanted substance boils and evaporates 2. ( almost of the unwanted liquid will evaporate likewise) and rises up the column. 3. The substance will condense on the beads in the column cause them to heat. 4. When the beads reach a certain temperature when the wanted liquid wont condense anymore (Thats the boiling point) it will rise while the unwanted liquid will condense and drop.The wanted liquid will make its means through the condenser where it will condense and drop down in the beaker. 7. Chromatography This method is used to separate a mixture of substances. For example you smoke use it to find how many obscure substances there are in black ink. step 1. throw the black ink on to the focus on off filter paper and allow it to dry. 2. Drop water on to the ink spot, one drop at a convicti on. 3. Suppose there are three rings yellow, red and blue. This shows the ink contains 3 colored substances. The substances travel across the paper at different rates.Thats why they separate into rings. The filter paper showing the separate substances is called a chromatogram. This method works because different substances travel at different speeds because they take up different levels of attraction to it. Uses of chromatography Separate mixtures of substances Purify a substance by separating the impurities from it Unit 2 The portion Identify a substance Atoms are the smallest particles. apiece atom consists of a nucleus and a defame of particles called electrons that whiz around the nucleus. An fraction is a substance that contains only if one kind of atom.The periodic table is the map/address book for parts where each element is given a symbol (E. G. K for potassium). The group of elements that let similar properties are put in a numbered column. For example, if you k instantly how one element in group 1 behaves, you can easily remember how the others in the said(prenominal) group will behave. The rows are called periods. The gig-gag line separates metals from non-metals, with the non-metals on the right. So around elements are metals. A compound contains atoms of different elements Joined together where the atoms are chemically combined.For example carbon dioxide is a compound of carbon and oxygen (1 carbon and 2 oxygen molecules). The symbol for compound is made from the symbols of the elements in it. So the systemula for carbon dioxide is CO. Isotopes and Radioactivity You can identify an atom by the number of protons in it. For example, only atomic number 11 atoms have 11 protons. Isotopes are atoms of the same element, with different numbers of neutrons. Some isotopes are radioactive. That means its nucleus is unstable, sooner or afterwards the toms breaks down or tumbles, giving out light beam in the form of rays and tiny particles, as swell up as large amount of energy.Like carbon-14, a number of other elements have radioisotopes that occur naturally and lastly decays. unless the other two isotopes of carbon (like most natural isotopes) are non-radioactive. You can know when radioisotopes decay by looking at there fractional life. Radiation affects humans as it may causes them shaft of light sickness but radiation also has some uses. Uses of radiation 1. Check for leaks in pipes (industry) This is done by adding a radioisotope to the oil or gas. At a leak, the radiation is detected using an instrument. Radioisotopes used in this way are called tracers. 2. N cancer manipulation (Medical) Radioisotopes can cause cancer but merely also can cure it. Using actinotherapy the radioisotope will decay and give out rays that can kill cancer cells. These rays will be aimed on the dot at the cancer cells. 3. To find the age of old remains A tiny percentage of a living thing contains carbon-14 atoms. When living t hing dies it no longer takes in new carbon atoms. alone existing carbon-14 atom decay over time we can measure the faint radiation from them. How electrons are arranged The electrons in an atom circle fast around the nucleus, at different levels from it.These energy levels are caller electron display cases. The further the shell is from the nucleus, the higher the energy level. Each shell can demand a limited number of electrons. First shell can mince up to 2 electrons game shell can hold up to 8 electrons The third shell can also hold up to 8 electrons Electronic contour means the arrangement of electrons in an atom. Argon has the electronic configuration 2,8,8 Magnesium has the electronic configuration 2,8,2 Important points The shells drive in order, from lowest energy level to highest energy levelAll the elements in a group have the same number of electrons in their out shells. These are called valency electrons. The group number is the same number of outside shell electrons The period number shows how many shells there are. If an element posses a in full outer shell, the element become enervative Unit 3 Atoms combining nigh elements form compounds because they want a full outer shell and to achieve that they must fight down with other atoms. For example, sodium has Just one electron in its outer shell.It can obtain a full outer shell by losing this electron to anther atoms and by that it becomes a sodium ion. Now because sodium anomic a electron It now has 10 electrons but 11 protons So it has a 1 optimistic charge. An ion is a charged particle. It is charged because it has an unequal number of protons and electrons. The noggin constipate Sodium and chlorine react together sodium gives its electron to chlorine. Now both elements have a full outer shell, but with a charge. Now they are ions. Sodium now has 10 electrons but 11 protons so it has a arbitrary charge.Chlorine now has 18 electrons but 17 protons so it has a negative charg e. The two ions have opposite charges, so they attract each other. The force of attraction betwixt them is strong. It is called an ionic bond. When sodium reacts with chlorine, billions and billions of sodium and chlorine ions form and they attract each other. But the ions dont stay in pairs. They cluster together so that each ion is surrounded by 6 ions of opposite charges. The pattern grows until a giant structure of ions is formed. The boilers suit charge of the structure is O since 1 positive charge and 1 negative charge rot each other.The ionic bonding is only between metals and non-metals. Important notes Hydrogen and the metals form positive ions Non-metals form negative ions, and their names end in -did host 4 and 5 do to usually form ions because they would have to lose or gain some(prenominal) electrons and that takes too much energy Group O elements do not form ions they already have full outer shells Some of the transition metals form more than one ion. Some ions can be formed from groups of Joined atoms. These are called compound ions. Properties of ionic compound 1.Ionic compounds have high melting and boiling points. This is because ionic bonds are very strong, so it takes a lot of heat energy to break up the lattice. 2. Ionic compounds are usually soluble in water. The water molecules can attract the ions away from the lattice. The ions can then move freely, surrounded by water molecules. 3. Ionic compounds can conduct electricity when they are melted or dissolved. When melted the lattice breaks up and the ions are free to move. Since they are charged, this means they can conduct electricity.The solutions of ionic compounds conduct electricity too because they are also free to move. The covalent bond Giving and losing an electron is not the only way to gain full outer shells since atoms can also share electrons. Covalent bonding is for non-metals only since only non-metals need to gain electrons. A molecule is a group of atoms held toge ther by covalent bonds. When a pair of electrons is shared, it is called a single covalent bond, or Just single bond. When 2 pairs of electrons are shared, it is called a figure of speech covalent bond, or Just double bond.When 3 pairs of electrons are shared, it is called a triple covalent bond, or Just triple Covalent compounds A covalent compound is when atoms of different elements share electrons with each other. The molecules in a covalent compound isnt flatbed because each electron repel each other and try to get as far apart from each other. Molecular substances Most molecular substances are gases or liquids at room temperature. Molecular lids are held in a lattice but the forces between the molecules are weak. All molecular solids have similar structure.The molecules are held in regular pattern in a lattice. So the solids are crystalline. When you cool down a molecular liquid or gas the molecules lose energy so they start paltry slowly and at the freezing point, they form a lattice (a good example would be ice) Properties of covalent bonding 1. Covalent compounds have low melting and boiling point This is because the forces between the molecules are weak. 2. They do not conduct electricity This is because molecules are not charged, so they cannot conduct, even when melted