Chemistry Review Fall 2017

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Muriel Cunningham
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1 Chemistry Review Fall 2017 Element=the simplest form of matter on the periodic table (P.T.) Compound= two or more elements Mixture= two or more compounds Homogenous Mixture = perfectly mixed in equal amounts Heterogeneous Mixture= not perfectly mixed in unequal amounts Chemical or Physical change: Fill in the chart Example Burning wood Adding heat and boiling chemicals Chemicals mixing and forming bubbles Chemicals changing phases from solid to liquid to gas Chemicals mix and produce heat Grapes fermenting Iron rusting Salt dissolves in water Baking cookies Chemicals mixing and forming a precipitate Clear Chemicals mixing and turning a different or cloudy color Physical (P) or Chemical(C)

2 Protons/Neutrons/ Electrons on a Neutral atom : protons/atomic #=electrons; protons + neutrons=mass; Mass is more massive: Protons/atomic number 8 Fill in the chart neutrons Atomic mass electrons Element/ Symbol Gold/Au Sodium/Na Ions: Metals have a positive charge (cation), and have lost electrons (-): Na + has lost 1 electron. Non-metals have a negative charge (anion), and have gained electrons (-): O -2 has gained 2 electrons. Fill in the chart Ion Cation or Anion Protons Electrons K + Mg +2 Al +3 Cl - Ca +2 S -2 P -3 Br -

3 Isotopes: mass and neutrons change, protons do not change, numbers given represent mass Fill in the chart Isotope Mass # Proton # # of Neutron s 15 N 14 N 16 O 17 O 1 H 2 H 3 H 12 C 14 C Metal, non-metal or metalloids: Fill in the chart Element Name of element metal or non-metal or metalloid O Cl Si Ag Na Be Sb C S Al Cu Ca Mg N Qualities that identify this: pick one A. Not lustrous, poor conductors of heat and electricity, nonreactive B. Properties of metals and non-metals C. Conducts heat and electricity, malleable, lustrous, ductile, reactive

4 Electrons, Light and Energy: E=hxf and c=fx where h=6.63 x Jxsec and c=3.0 x 10 8 m/sec; f=hz or 1/s and = meters (m), also convert nm to m first using 1 nm= 1x 10-9 m: What to Remember: 1. if an electron gains a quantum of energy, it increases a level(climbs the stairs) and energy is absorbed and no light is emitted and 2. If an electron loses a quantum of energy, it decreases a level(falls down the stairs) and energy is emitted in the form of light. Energy : E unit is Joules(J) Frequency: f Unit is Hertz(Hz) Wavelength : Unit is meter(m) 656 nm 4.0 x J 434 x 10-9 m 6.67 x Hz 4.10 x 10-7 m 5.45 x10 14 Hz 486nm Trends in electrons 1. Looking at the periodic table from left to right a. Atomic radius decreases, ionization energy increases, electronegativity increases, ionic size (cations and anions) decreases 2. Looking at the Periodic Table from top to bottom a. Atomic radius increases, ionization energy decreases, electronegativity decreases and ionic size increases Electron Configuration: First number is the level, letter is the shape or sublevel, and superscript is the number of electrons: add the superscripts and they will add up to the atomic number: So 1s 2, 2s 2, 2p 6, 3s 2, 3p 6 4s 2 3d 10 is atomic number 30 belonging to Zinc Order is 1s, 2s, 2p, 3s,3p, 4s, 3d, 4p,5s,4d,5p,6s, etc.; s=2 max, p=6 max, d=10 max, f=14 max. s group are alkali metals and alkaline earth metals and will transfer or lose electrons more easily than p, many in the p group are non-metals and take electrons. d group are transition metals. 1 st level max is 2: 1s has 2 max=2 2 nd level max is 8: 2s has 2 max and 2p has 6 max; 2 +6 =8 3 rd level max is 18: 3s has 2 max, 3p has 6 max and 3d has 10 max; = 18 4 th level max is 32: 4s has 2 max, 4p has 6 max, 4d has 10 max and 4f has 14 max; =32

5 Naming and Ions: Two elements always end in ide, three or more many times end in ite or ate Ions are cations with a positive charge, metals and NH 4+ and anions with a negative charge, mostly nonmetals. Remember: When writing a compound formula with cations and anions, the cation is always written first So sodium chloride is NaCl, potassium bromide is KBr Charges of ions in an ionic compound cancel each other out so the compound is neutral, the charge of the ion becomes its partners subscript if charges don t equal each other. Parentheses are required if there is more than on polyatomic ion. So magnesium nitrate is formed with Mg +2 and NO 3 -, There will be one magnesium and two nitrates Mg(NO 3) 2 For 2 non-metals: Use mono, di, tri, tetra, penta, hexa, hepta, oct, nona, or deca as a prefix of your element in the compound except don t use mono on the first element So CO 2 is carbon dioxide and Cl 2O 8 is dichlorine octaoxide Naming acids and bases and information: Acids (sour, electrolytes, turns most indicators red)always start with Hydrogen except water which is neutral 1. HCl, HBr, HF are Hydro ic acids, where is chlor, brom and fluor respectively 2. If a polyatomic anion ends in ate = ic acid, H 2SO 4 is sulfuric acid 3. If a polyatomic anion ends in ite = ous acid, H 2SO 3 is sulfurous acid Bases (bitter, slippery, electrolytes, turns most indicators blue)end in hydroxide except for NH 3 which is ammonia, NaOH is sodium hydroxide, KOH=potassium hydroxide Name the following: HCl, Na 2SO 4, Mg 3(PO 4) 2, NaBr, NO 2, CO 2, H 2CO 3, Al(OH) 3, Ca 3P 2, K 2O Write the formulas for the following: sodium oxide, potassium phosphate, dichlorine octoxide, hydrofluoric acid, beryllium sulfide, lithium nitride, calcium hydroxide, sulfuric acid, magnesium nitrate, sulfur trioxide

6 Fission and Fusion: 1. Nuclear fission is the splitting of a massive nucleus into photons in the form of gamma rays, free neutrons, and other subatomic particles. In a typical nuclear reaction involving 235 U and a neutron: U + n = U followed by U = Ba Kr + 3n MeV 2. Nuclear fusion is the reaction in which two or more nuclei combine, forming a new element with a higher atomic number(more protons in the nucleus). The energy released in fusion is related to E = mc 2 (Einstein s famous energy-mass equation). On Earth, the most likely fusion reaction is Deuterium Tritium reaction. Deuterium and Tritium are isotopes of hydrogen. 2 1Deuterium + 3 1Tritium = 4 2He + 1 0n MeV Electrons and bonding: Valence electrons are the outermost electrons in elements that bond The number of valence electrons = the number in front of the A columns on the P.T. Ionic bonds: Ionic compounds are usually solid, soluble in water, good conductors of electricity with high melting points Ionic compounds, the electrons from the metal are transferred to the nonmetal, so the non-metal has a total of eight valence electrons Show ionic bonding with Lewis-dot structure for sodium chloride (NaCl), magnesium bromide(mgbr 2), potassium sulfide (K 2S), lithium nitride(li 3N) and aluminum oxide (Al 2O 3). See page A Covalent bonds: Covalent compounds are usually solid, liquid or gas, mixed solubility, poor electrical conductors and have a low melting point Covalent compounds, two non-metals share electrons, each time they share, it counts as two for each element the shared electrons touch. Individual pairs left are called lone pairs and counted individually. Show covalent Bonding with Lewis-dot structure for water (H 2O), hydrogen gas (H 2), ammonia(nh 3), carbon dioxide(co 2), methane(ch 4)and oxygen gas(o 2). See page A

7 Density: Water has a density of 1 g/ml, Density =mass/volume or D=M/V, units are g/ml or m/cm 3 If an object had a density more than water, 1.5 g/ml, it will sink. If an object has a density less than water 0.75g/ml, it will float. Density(g/mL or Mass (g) Volume(ml or cm 3 ) g/cm 3 )/substance 1/water /glycerol 50 /mercury /silver 12 /copper 89 10

8 Water example, density = 1 g/ml Density graph example:

9 Pick a point, draw a line to mass, record this number (m). From the same point, draw a line to volume, record this number(v). Repeat for 2 to 3 points on the same line. D=m/v, calculate density(d). Compare this to a density chart to determine the material based on density.

Chapter 5 BONDING AND MOLECULES

Chapter 5 BONDING AND MOLECULES How Do Atoms Combine to Form Compounds? (5.1) Chemical bonds: a force of attraction between atoms or ions. Octet Rule: atoms tend to gain, lose, or share electrons in order