(1) Instructions:
Tell how many protons, neutrons, and electrons each element has based on the information given.

a.)

b.)

c.)

d.)

e.)

(2) Instructions:
Name these compounds.

a.) CuCl b.) NaF c.) MnO₂ d.) FeBr₂ e.) Fe₂O₃

(3) Instructions:
Find the formula for each chemical below.

a.) Sodium sulfate   b.) Vanadium (V) fluoride    c.) Mercury (I) chloride   d.) Tin (II) fluoride   e.) Cobalt (III) nitrate

(1 Answers)

1. The atomic weight is 16 amu. Since we know that oxygen, with a 8, has 8 protons (that is the definition of a an atomic number), we can then deduce that oxygen has 8 neutrons (16-8 = 8). Final answer? 8 protons, 8 electrons, and 8 neutrons. Please note that in an elemental state, the number of electrons and protons will always be equal.
2. With an atomic weight of 11 amu, along with an atomic number of six, boron has 5 neutrons. (11 amu - 6 protons = 5 neutrons)
3. 4 protons, 4 electrons, and 5 neutrons
4. 3 protons, 3 electrons, and 4 neutrons
5. 11 protons, 11 electrons, 12 neutrons

(2 Answers)

1. By the rules, this is Copper Chloride. But copper can have different charges, so you must figure what the charge on this one is. Let's see: you know chloride can have only one value, and that's a -1. So if they must add up to zero, Cu must be +1. The answer is copper (I) chloride.
2. This is sodium and fluorine, so the name is sodium fluoride. Sodium can only be +1, so there is no need for roman numerals.
3. The name is Manganese Oxide, but a roman numeral is necessary, since it's a transition metal. In this case, manganese is a transition metal, so it needs a roman numeral. Let's start with oxygen: Each oxide ion has a charge of -2, and there are 2 of them. So the total charge due to oxide is -4. The single manganese ion must compensate for this, so its charge must be +4. The name is manganese (IV) oxide.
4. Same here. It needs a roman numeral. Br is -1, and 2 of them, so Fe must be +2. Name is Iron (II) Bromide.
5. e.This one's a little bit different, but the same concepts apply. You start with the oxygens. 3 of -2 ions make it a total of -6 charge due to oxide. So the two irons must compensate. If two of them must equal +6, each must be...+3!!! It should be no surprise. So the name of this is Iron (III) Oxide.

(3 Answers)

Answers

1. The ions are Na⁺ and SO₄^2-. But Na has only +1, and SO₄ is -2. So you need two Na's to make up for that -2. The answer is Na₂SO₄.
2. The ions are V⁵⁺ and F^-. You know the +5 of vanadium by the (V). So you need 5 fluorines to make up for that +5. The answer is VF₅.
3. Mercury is the weird ion. Since it's (I), then the ion must be Hg₂²⁺. And since there is a +2, you need two Cl-'s to balance. The answer is Hg₂Cl₂.
4. Tin is +2, so you need 2 F's to balance. Answer is SnF₂.
5. Cobalt is +3, and nitrate is -1. Need three nitrates to balance, so answer is Co(NO₃)₃.