1.1 Atoms

Question 1

define atoms

Answer 1

atoms are the smallest thing that exists

Question 2

define elements

Answer 2

an element is a substance made up from only one type of atom

Question 3

define compounds

Answer 3

a compound is a substance made up of two or more elements chemically combined.

Question 4

define mixtures

Answer 4

a mixture is a substance made up of two or more elements NOT chemically combined so can be separated by physical processes

Question 5

Explain the history of the atom

Answer 5

1800- John dalton
discovered that atoms were the smallest thing that existed

1897- j.j Thompson
discovered the ‘plum pudding model’ which was a positive-charged ball which has negative charged particles spread over it.

1911- Ernest Rutherford
discovered that there was a positive nucleus at the centre.

1913- Neils Bohr
discovered that electrons moved in orbits and the positive charge of the nucleus was made up of particles called protons.

1932- James Chadwick
discovered the neutron which is found inside the nucleus with the proton.

Question 6

Give the relative charge of each subatomic particle

Answer 6

proton- +1
neutron- 0
electron- -1

Question 7

define atomic number

Answer 7

atomic number = number of protons

Question 8

define mass number

Answer 8

mass number = number of protons + number of neutrons

Question 9

give the relative mass of each subatomic particle

Answer 9

proton- 1
neutron- 1
electron- very small (1/200)

Question 10

define isotopes

Answer 10

isotope contains the same amount of protons but different amount of neutrons

Question 11

how do you calculate:
number of protons-
number of neutrons-
number of electrons-

Answer 11

to calculate:
number of protons = atomic number
number of neutrons = mass number - atomic number
number of electrons = atomic number (for atoms, not ions)

Question 12

define relative atomic mass

Answer 12

The relative atomic mass of an element is an average value that takes account of the abundance of
the isotopes of the element

Question 13

formula for relative atomic mass?

Answer 13

relative atomic mass =

total mass of all atoms of element/ total number atoms of that element

Question 14

describe the electronic structure of an atom

Answer 14

2,8,8,2

Question 15

How are elements arranged in the periodic table?

Answer 15

Elements are arranged in the periodic table by:

• atomic (proton) number
• how many electrons are in their outer shell

Question 16

explain the development of the periodic table

Answer 16

Before the discovery of protons, neutrons and electrons scientists attempted to classify which group elements belonged in with their atomic weights.

Mendeleev overcame problems with undiscovered elements and so left gaps for them to be later investigated.

Question 17

how do you know if an element is non-metal or metal?`

Answer 17

elements that react to form positive ions are metals

elements that react to form negative ions are non-metal

Question 18

where are non-metals and metals positioned in the periodic table?

Answer 18

non-metals are found towards the top and right.

metals are found towards the bottom and left.

Question 19

Group 0 information

Answer 19

group 0:

• it is named the noble gases
• it is unreactive as it has a full outer shell
• their boiling points increase as you go down the group

Question 20

Group 1 information

Answer 20

group 1:

• they are known as the alkali metals
• have a low density
• react with non-metals to form ionic compounds [these compounds are white solids which dissolve in water to form colourless solutions]
• react with water, releasing hydrogen
• form hydroxides that dissolve in water to give alkaline solutions
• the reactivity of the elements increase going down the group

Question 21

Group 7 information

Answer 21

group 7:

• they are known as the halogens
• have 7 electrons in their outer shell
• are non-metals
• the boiling/melting point increases further down the group
• the reactivity decreases going down the group
• a more reactive halogen can displace a less reactive halogen

Question 22

comparison of group 1 (alkali metals) with transition metals

Answer 22

similarities:

• thermal conductor
• electrical conductor
• react with non-metals to form ionic compounds
• shiny when polished

differences:
(alkali metals) (transition metals)
-low melting points -high melting points
- low density -high density
-very soft -hard
-very reactive -low reactivity
-react to form 1+ ions -react to form ions with
-compounds are white different charges
-do not act as catalysts -compounds are colour
-are often catalysts