chapter 2 - atoms, ions, and compounds

Question 1

relative mass of 3 sub-atomic particles

Answer 1

proton: 1
neutron: 1
electron: 1/1836 (negligible)

Question 2

relative charge of 3 sub-atomic particles

Answer 2

proton: 1+
neutron: 0
electron: 1-

Question 3

how is the periodic table ordered?

Answer 3

in order of the number of protons in the nucleus (atomic number)

Question 4

what are isotopes?

Answer 4

atoms of the same element with the same number of protons but a different number of neutrons

Question 5

what are the chemical notations for isotopes? (A and Z)

Answer 5

• A = mass number = number of protons + neutrons
• Z = atomic number = number of protons

Question 6

how do chemical and physical properties differ with different isotopes?

Answer 6

• different isotopes of an element react in the same way because they have the same number of electrons in the outer shell; the number of neutrons has no effect on reactions of an element
• there may be different physical properties due to the different mass number (eg. higher mass = higher melting/boiling point and density

Question 7

what is the definition of relative isotopic mass?

Answer 7

the mass of an atom of an isotope, compared to 1/12th of the mass of an atom of carbon-12

Question 8

what is the definition of relative atomic mass (Ar)?

Answer 8

weighted mean mass of an atom of an element, compared to 1/12th of the mass of an atom of carbon-12

Question 9

what does weighted mean mass take into account of?

Answer 9

• the percentage abundance of each isotope
• the relative isotopic mass of each isotope

using the percentages of the isotopes, the Ar can be calculated

Question 10

what is mass spectrometry used for finding?

Answer 10

• the relative isotopic masses of an isotope
• the relative abundance of the different isotopes
• the relative atomic mass of an element

Question 11

what are the 5 stages of mass spectrometry? (victor is a daft duck!)

Answer 11

1. vaporisation
2. ionisation
3. acceleration
4. deflection
5. detection

Question 12

what are the charges of the elements in groups?

Answer 12

• group 1 = 1+
• group 2 = 2+
• group 5 = 3- (eg. N, P)
• group 6 = 2- (eg. O, S)
• group 7 = 1-

Question 13

what are the charges of the transition metals?

Answer 13

• Al³⁺
• Zn²⁺
• Ag⁺
• Cu⁺ or Cu²⁺
• Fe²⁺ or Fe³⁺

Question 14

how do you name a binary compound?

Answer 14

use the name of the first element but change the ending of the second element to -ide

eg. calcium nitride

Question 15

what are the charges of common polyatomic ions?

Answer 15

ammonium = NH₄⁺

hydroxide = OH⁻
nitrate = NO₃⁻
nitrite = NO₂⁻

carbonate = CO₃²⁻
sulfate = SO₄²⁻
sulfite = SO₃²⁻

phosphate = PO₄³⁻

Question 16

what elements exist as diatomic molecules?

Answer 16

H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂

Question 17

what are the 2 elements that exist as small molecules?

Answer 17

• phosphorus, P₄
• sulfur, S₈

it is normal to write sulfur as S in equations, as otherwise every formula in the equation has to be multiplied by a factor of 8