1.1 Atomic Structure - The Atom

Question 1

Charge of proton:

Answer 1

+ 1.60 x 10^-19

Question 2

Charge of neutron:

Answer 2

0 C

Question 3

Charge of electron:

Answer 3

• 1.60 x 10^-19

Question 4

Relative charge of proton:

Answer 4

1+

Question 5

Relative charge of neutron:

Answer 5

0

Question 6

Relative charge of electron:

Answer 6

1-

Question 7

Mass of proton:

Answer 7

1.67 x 10^-27

Question 8

Mass of neutron:

Answer 8

1.67 x 10^-27 kg

Question 9

Mass of electron:

Answer 9

9.11 x 10^-31

Question 10

Relative mass of proton:

Answer 10

1

Question 11

Relative mass of neutron:

Answer 11

1

Question 12

Relative mass of electron:

Answer 12

1/1836

Question 13

Atomic number:

Answer 13

The number of protons in the nucleus of an atom.

Question 14

Why does the atomic number also tell you the number of electrons in an atom?

Answer 14

The atom is neutral therefore it must have an equal number of protons and electrons.

Question 15

Mass number:

Answer 15

The sum of protons and neutrons in an atom.

Question 16

Number of neutrons:

Answer 16

= mass number - atomic number

Question 17

What are isotopes?

Answer 17

Atoms of the same element (same atomic number) but with a different mass number as they have the same number of protons but a different number of neutrons.

Question 18

Chemical properties of isotopes:

Answer 18

Chemical properties of different isotopes are the same as they have the same number and arrangement of electrons.

Question 19

Physical properties of isotopes:

Answer 19

Physical properties of different isotopes differ because of their masses (e.g. density, rate of diffusion)

Question 20

Relative atomic mass:

Answer 20

The average mass of an atom of an element compared to the 1/12th of the mass of the carbon-12 isotope.

Question 21

Relative molecular mass:

Answer 21

The average mass of a molecule of an element compared to the 1/12th of the mass of the carbon-12 isotope

Question 22

Relative isotopic mass:

Answer 22

The average mass of an isotope of an element compared to the 1/12th of the mass of the carbon-12 isotope

Question 23

Why are relative masses compared to carbon-12?

Answer 23

Hydrogen was originally chosen to be measured against other elements’ masses but it had a low accuracy of atomic mass measurement so carbon was chosen as it was more practical being a solid.

Question 24

Ar of an element calculation:

Answer 24

sum (isotopic mass x % abundance) / 100

Question 25

% abundance of an isotope calculation:

Answer 25

(n x y) + (m x (100 - y) / 100

Question 26

19th Century, John Dalton model:

Answer 26

Described atoms as solid spheres and said that these spheres made up different elements

Question 27

1897, J.J. Thomson model:

Answer 27

Discovered the electron which showed that atoms weren’t solid and indivisible. Known as ‘plum pudding’ model

Question 28

1909, Ernest Rutherford model:

Answer 28

With his students Hans Geiger and Ernest Marsden, he conducted the gold foil experiment - fired alpha particles at a very thin sheet of gold. Discovered the atom to have a very small positively charged nucleus with a ‘cloud of electrons surrounding it; most of the atom is empty space

Question 29

Explanation of gold leaf experiment:

Answer 29

Plum pudding model suggested most alpha particles would be slightly deflected by the positive ‘pudding’ of the atom but most passed through with a small number being deflected backwards. This disproved the plum pudding model as the atom must be mostly empty space.

Question 30

Niels Bohr model:

Answer 30

Scientists realised that if the electrons were in a ‘cloud; they would spiral into the nucleus causing it to collapse. Therefore, Bohr proposed a model in which the electrons are arranged in fixed energy shells. When electrons move between shells, EM radiation with fixed energy is emitted of absorbed.

Question 31

Refined Bohr model:

Answer 31

Scientists observed that not all electrons in the same shell had the same energy leading to the discovery of sub-shells. This is a useful model as its simple and explains observations such as bonding