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Matter

Matter Chemical manufacturing in Ont. Is the province’s third largest manufacturing industry!! In 2008 – 50 000 jobs and $22 billion (mostly plastics). MATTER: anything having a mass and taking up space

vladimir-neveah
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Matter

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  1. Matter • Chemical manufacturing in Ont. Is the province’s third largest manufacturing industry!! In 2008 – 50 000 jobs and $22 billion (mostly plastics). • MATTER: anything having a mass and taking up space • PHYSICAL PROPERTIES: Table 4.1 – anything used to describe physical appearance and composition. • - list them… • CHEMICAL PROPERTIES: Table 4.2 – describes the ability of a substance to change into a new substance or substances. • - list them… • all matter classified as either pure substance (only one kind of matter). Including elements, compounds or a mixture (combination of pure substances). Including homogeneous and heterogeneous mixtures.

  2. Atomic Theory • study of the nature of atoms • SUBATOMIC PARTICLES: • Electrons: Charge -1, mass 1, orbits/shells • Protons: Charge +1, mass 1836, nucleus • Neutrons: Charge 0, mass 1837, nucleus • Bohr diagrams represent atom structure – Ex: Na • Electrons surround nucleus in shells (each shell with it’s specific energy level). 1st shell: 2 e; 2nd shell: 8 e; 3rd shell: • Electrons = protons in every atom • Electrons in outermost shell = valence electrons

  3. The Periodic Table • Periods: horizontal rows • Groups: vertical columns – have similar properties • Metals on left • Non-metals on right • Metalloids: separate metals and non-metals with a staircase of elements (also have properties of metals and non-metals). • GROUPS: • Group 1: Alkali metals (soft silvery, react easily with H20 and O2 in air. NOT hydrogen. • Group 2: Alkaline Earth Metals: silver-grey metals, harder and less reactive than alkali metals. • Group 17: Halogens. Coloured non-metals, very reactive. • Group 18: Noble gases. Non-metals, unreactive, odourless gases.

  4. Trends in the arrangement of Electrons: • same group = same # valence electrons • group 18 = full shell

  5. Compounds: Ionic and Molecular • ION: an atom or group of atoms with an overall charge (+ or -) • Ionic compound: between + and – ions (metals and non-metals). • transfer of electrons to get full valence shells • Ex: NaCl • PROPERTIES: • at room temp. are hard, brittle solids • crystals with alternating +ve and –ve ions • high melting points • when dissolved in water = good conductors

  6. IONS: charged atom • Multivalent metals: metals that can have differing #’s of valence electrons. Shown with roman numerals. Ex: copper (II) chloride. CuCl2 subscript tells us which valence it is. • Polyatomic ions: group of atoms, usually including different elements that act as a single ION. • NAMING ionic compounds: • Metal ion first. • Non-metal ion second. Ending changes from “ine” to “ide”. • Ex: Calcium chloride • Ex 2: Name the following: Na+1 and F-1 Ca+2 and F-1 Multivalent: naming includes roman numeral Ex: PbI2 (I has a charge of -1) Polyatomic: metal first then polyatomic ion. The ending remains the same as the name of the polyatomic ion. Ex: NaOH * Some polyatomic ions remain in brackets since there is more than one. Ex: Al(OH)3

  7. Writing Formulas for Ionic compounds • Look at ions • Either use the criss cross method or determine how many of each atom is needed to balance out the charges • Ex: Na+1 and Cl-1 • Ex: Mg+2 and Cl-1 • Ex: Ca+2 and PO43-

  8. Molecular Compounds • Covalently bonded (sharing electrons) • between two non-metals • Include diatomic molecules (made up of two atoms of the same element). Often gases. Ex: Cl2 and H2 • See table 4.11 • Properties: • often soft • when dissolved in water, do NOT conduct electricity • low melting points • Need to use prefixes for naming: • Mono – 1 • Di – 2 • Tri – 3 • Tetra – 4 etc. • Rules for naming: • Name the first element • Name 2nd element with suffix “ide” • Add prefixes to indicate the number of each atom. Don’t use mono for one atom unless it is the 2nd element. • Ex: SO2, CO2, CO

  9. Chemical Reactions What is the reaction in an air bag?? Pg. 173 Chemical Reactions are responsible for everything from glow sticks to ice packs etc. Starting materials: REACTANTS New substances: PRODUCTS Word equation: sodium hydroxide combines with hydrochloric acid to produce sodium chloride and water. Formula equation: NaOH + HCl NaCl + H2O • Chemical Change: • Precipitate formed • heat,light given off or absorbed • new substances formed • gas produced • change in colour

  10. Conservation of Mass Total mass of reactants = total mass of products Thus, we MUST balance all chemical equations. Ex: H2(g) + O2(g) H2O(l) But not balanced! 2H2(g) + O2(g) 2 H2O(l) Need to count all atoms of EACH element on the reactant side of the equation and make sure they equal the product side atoms.

  11. Acids and Bases Acids can be both harmful (carbonic acid, H2CO3) and useful (DNA). Same with bases. pH scale is a logarithmic scale telling us how acidic or basic a substance is. • Neutral pH: 7.0 (pure water) • Acid: pH less than 7.0 • Base: pH greater than 7.0 • Acid – base indicators: changes colour when added to acid or base • Litmus paper: red paper turns blue in bases. Blue litmus paper turns red in acids. No colour change in a neutral solution. • Universal indicator: mix of chemicals that change colour with a wide range of pH • pH meter.

  12. Naming Acids: • Formula starts with H then start with prefix “hydro” and end with the first part of the name of the non-metallic element with a suffix “ic” and acid. EX: HF is hydrofluoric acid. • If formula contains polyatomic ions then start with the name of the ion and end with “ic” and acid. EX: H2SO4 is sulfuric acid. • Naming Bases: • Write the name of the positively charged metallic ion that is at the beginning of the chemical formula. • Add the word “hydroxide” • Ex: KOH Potassium hydroxide • Ex: NH4OH Ammonium hydroxide

  13. Neutralization Reactions • Soil pH – huge factor with crop success • Neutralization: acid + base salt + water • Ex: HCl (aq) + NaOH(aq) NaCl(aq) + H2O(l) • Applications: • Acid reflux, bee sting (formic acid ) with ammonia-based cream, calcium carbonate in soil, prepared foods slightly acidic = less bacteria • Environmental Applications: • Acid Precipitation: pH < 5.6 caused by SO2 and nitrogen oxides in the atm. They become sulfuric acid and nitric acid. From: iron/steel, fertilizer production etc. • EFFECT: corrodes buildings etc. forests, lakes, streams become acidic = loss of organisms.

  14. Neutralizing Acidic Lakes: add lime to water • 2HNO3(aq) + Ca(OH)2(s) Ca(NO3)2(aq) + 2H2O(l) • Very expensive • Reducing acid precipitation: Scrubbers at the top of smokestacks remove these gases. • 2. Heavy Metals • High atomic mass – As, Cu, Hg, Zn • causes kidney, lung diseases, bone and nervous system damage • Cu from engine parts, Ni in diesel fuel + gas etc. Ni + Cd in batteries. • Old mines – acid leaching from metals in soil. • Restoring soils: remove soil, add acid, collect metals, acid base = precipitate

  15. Types of Chemical Reactions • SYNTHESIS RXN: • Two elements combine = product • A + B C • Ex: 2Mg(s) + O2(g) MgO(s) * make sure to always balance your equations • 2. DECOMPOSITION RXN: • Compound is broken into two elements/simpler compounds • AB A + B • Ex: HgO(s) Hg (l) + O2(g) • 3. COMBUSTION RXN: • Hydrocarbons react with O2 to give CO2 and water. Inc. fossil fuels. • Ex: CH4 (g) + O2(g) CO2(g) + H2O(l) • Environmental implications (global warming, oil spills, fertilizers etc.). • 4. SINGLE-DISPLACEMENT REACTIONS • AB + C CB + A • An element reacts with an ionic compound and becomes part of the ionic compound • 3CuCl2(aq) + 2Al(s) 2AlCl2(aq) + 3Cu(s) • A non-metal replaces a non-metal or a metal replaces a metal.

  16. 5. DOUBLE DISPLACEMENT REACTIONS • Positive or negative ions in two dissolved ionic compounds switch places. • AB + CD AD + CB • reactants and products are all compounds • may result in a precipitate • Ex: Mg(OH)2(aq) + AgNO3(aq) Mg(NO3)2(aq) + AgOH(s) • NEUTRALIZATION RXN • double displacement • Acid + Base Salt + Water • * Summary of reaction types is on pg. 236

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