Module 2: Atoms, ions and compounds

Question 1

Nucleons are held together by …
Protons + electrons are held together by ..

Answer 1

Strong residual forces
Strong electrostatic forces

Question 2

Mass number =
Atomic number =

Answer 2

Ar
Z

Question 3

Chemical properties depend on …

Answer 3

Number and arrangement of electrons. Isotopes have same chemical properties as same no. electrons. No. neutrons have no effect on reaction.

Question 4

Physical properties depend on …

Answer 4

Mass of atom, so isotopes have slightly different physical properties e.g. bmp.

Question 5

To calculate no. electrons in a shell …

Answer 5

2n squared. n is the number of shells.

Question 6

Hydrogen atom -
Deuterium atom (D2O) -
Tritium atom (T2O) -

Answer 6

1 proton, o neutron, 1 electron.
1 proton, 1 neutron, 1 electron.
1 proton, 2 neutrons, 1electron.

Question 7

Normal water is the …
Heavy water is …

Answer 7

Hydrogen isotope.
Deuterium. Used to control nuclear processes.

Question 8

Why does deuterium have higher bmp and density than hydrogen?

Answer 8

Deuterium has greater mass so more surface area for contact so greater attraction between electrons and proton of other atom. If all water were heavy water, we would see ice more often.

Question 9

Oxygen-16 means …

Answer 9

Mass number is 16.

Question 10

Define cation.
Define anion.

Answer 10

+ charged with fewer electrons.
- charged with more electrons than protons.

Question 11

What is the carbon-12 isotope?

Answer 11

International standard for the measurement of atomic masses.

Question 12

Relative mass compares …

Answer 12

Th mass of 1 atom to carbon-12

Question 13

Standard atomic mass is …
Mass of carbon-12 is …

Answer 13

1u
12u

Question 14

Define relative isotopic mass.

Answer 14

Mass of an isotope relative to 1/12 the mass of an atom of carbon-12. RIM = mass no!

Question 15

RIM has …
It is usually …

Answer 15

No units and it’s a ratio of 2 masses.
A whole number.

Question 16

Work out masses to …

Answer 16

1dp

Question 17

Define relative atomic mass (Ar).

Answer 17

Weighted mean mass of an atom of an element relative to 1/12 the mass of carbon-12.

Question 18

Is RAM a whole number?

Answer 18

No, as it’s an average.

Question 19

RAM depends on …

Answer 19

% abundance of each isotope, RIM of each isotope.

Question 20

Relative molecular mass (Mr) is used for …

Answer 20

Simple molecules (H2O, CO2). Just add up RFM of each.

Question 21

Relative formula mass is the …

Answer 21

Same as RMM but for giant structures (ionic).

Question 22

What is the mass defect?

Answer 22

Small amount of mass loss due to strong nuclear force holding protons + neutrons.

Question 23

What does a mass spectrometer do?

Answer 23

Produce mass spectra, which identify RIM and abundances of each element, thus RAM.

Question 24

What did JJ Thompson discover?

Answer 24

Plum pudding model - positively charged sphere with negative electrons in it.

Question 25

What did Rutherford do in the gold foil experiment?

Answer 25

He fired + charged alpha particles to a thin sheet of gold foil. Most particles passed straight through and some deflected back.

Question 26

What did Rutherford state?

Answer 26

1. Tiny, positively charged central nucleus, surrounded by electrons.
2. Most of the atom is empty space.

Question 27

What did Bohr realise?

Answer 27

Electrons would be attracted to the nucleus, so he proposed that electrons are in shells and each shell has a fixed energy.

Question 28

What else did Bohr state?

Answer 28

Atoms can react to gain an outer shell.

Question 29

When electrons move between shells …

Answer 29

EM radiation is emitted or absorbed.