Study+Guide+for+First+Semester

Density= mass over volume D=m/v. 12.50g/4.6ml=2.717 [When there is a decimal point start from nonzero number from the left to right.] __2__.__0__ __1__ __7__g/ml
 * 1. The answer is 4

[Rule for division and multiplication] - the answer can only have the same number of SF's (Significant digits) as the measurement with the least SF's. Answer: 2.7g/ml

2.** **The answer is 3 Rule for significant when there is no decimal. From left to right, starting with the first nonzero number you can count on each digit 1003g __1__ __0__ __0__ __3__g Atlantic-Pacific rule: < > If the decimal point is** **present count from the** **Pacific(left) If the decimal is** **absent count from the** **Atlantic (right)

3.** **The answer is 3 Cu is an element Sn is an element matter -mixtures -pure substances -compound -element Compounds:elements chemically combined in a fixed ratio.

4.** **The answer is 2 Pass all substances through a filter, that separates the sand and salt. Evaporating the water will get rid of all the water and split the sand and water.

5.** **The answer is 4 Distillation=boiling point Take crude oil and heat it up. This separates the crude oil because it is a gas first.**

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 *  6) The correct answer is 3 because when you look at the periodic table, Krypton (Kr) is the only one element and cannot be decomposed chemically as far as water (H2O), ammonia (NH3), and methane (CH4). They are molecules that have more than one element and can be decomposed. **======

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 *  7) The correct answer is 1 because Ca is a solid and it has fixed positions, so its particles wouldn’t spread around, but Hg, He, and NaCl are either a liquid, a gas, or a aqueous meaning its particles will spread all over the place if it vibrates. **======

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 *  9) The correct answer is 2 because on the periodic table the atomic number is 19 and the atomic number equals the total number of electrons in an atom. **======

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 * 18. The answer is number 2 because an element with a certain mass number or atomic number emits a beta particle. Therefore Kr emits a beta particle. **======

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 * 19. the answer is 4 because neutron has the least amount of charge, positron has higher charge than neutron and alpha particle has the highest charge from the choices **======


(1) mass number (3) number of electron shells (2) atomic number (4) number of valence electrons**** (4) number of valence electrons: The valence electrons determines the atoms chemical properties or reaction.** (1) Decreases (2) Increases (3) Remains the same** H - C C – H What is the total number of electrons shared in the bond between the two carbon atoms? (1) 6 (2) 2 (3) 3 (4) 4** 51. Difference between the bonding of KCL and ammonia. ** ** Potassium Chloride : KCL. Ammonia : NH4
 * 30) Lithium and potassium have similar chemical properties because the atoms of both elements have the same:
 * 31) As an atom becomes an ion, its mass number:
 * (3) Remains the same: Electrons barely weigh anything compared to its other particles, protons and neutrons. An atoms mass number is basically found by adding protons and neutrons; electrons take no part in the mass number. And ions are only determined by how many electrons are lost or gained. So the mass of the atom remains the same.**
 * 32) In which reaction are electrons transferred from one reactant to another reactant?(1) 2Ca(s) + O2(g) = 2CaO(s)(2) AgOH(aq) + KCl(aq) = AgCl(s) + KOH(aq)(3) HCl(aq) NaOH(aq) = NaCl(aq) +H2O(l)(4) H3O(aq) + OH(aq) = 2H2O(l)**** (1) 2Ca(s) + O2(g) = 2CaO(s): (1) is a synthesis reaction.**
 * 33) Which formula represents an ionic compound?(1) H2O (2) KCl (3) NH3 (4)CH4**** (2) KCl: A metal is present**
 * 3****4) Given the structural formula:
 * (1) 6 because the line resembles 2 electrons being shared in a covalent bond. There are three bonds going on so therefore 6 electrons are being shared.**
 * 35) Which two substances are covalent compounds?(1) C6H12O6(s) and KI(s)(2) C6H12O6(s) and HCl(g)(3) KI(s) and NaCl(s)(4) NaCl(s) and HCl(g)**** (2) C6H12O6(s) and HCl(g): In numbers (1), (2), and (3), a metal is present and covalent compunds do not have metals present.

Ammonia is an ionic compound. For everyone one nitrogen, there are four hydrogens. Potassium Chloride is a covalent compound.

In ionic compounds, the electrons are transferred within the atoms. In covalent compounds, the electrons are shared within the atoms.

52. 19.9% of boron has a mass of 10.013 amu. 80.1% of boron has a mass of 11.009 amu.

(.199)10.013 = 1.992587 8.818209 (.801(11.009 = 8.818209 + __1.992587__ =10.810796

53. Am – 241. (243) +3 241Am -> 4He 237Np Am +4 95 2 93 95 +5 +6

54. The half life of Am-241 is 433 years, whereas Fr-220’s half life is 27.5 seconds. The Am-241 would make a far better substance since it lasts much longer than the Fr-220. Fr is not as radioactive as Am, as well.

55. Zn(s) + 2HCl(aq) -> _(s) + H2. Zn(s) + 2HCl(aq) -> ZnCl2(s) + H2. You have to balance the equation and make sure whatever is on one side, is equal to the other. You need to figure out which atoms go in the blank space, and what the subscript is, to make sure it is equal to the reactant side.

56. Answer= Ag, Au,Cu

57. Answer= Group 18

58. Answer= 173 neutrons

59. Answer= 118 electrons

60.Answer= **