Atoms Flashcards
1
Q
atom
A
- smallest part of an element that can exist
- radius of 0.1nm and have no charge
2
Q
element
A
- contains one type of atom
- represented by a symbol
3
Q
compound
A
- two or more chemically combined elements
- only separated into elements by chemical reactions
4
Q
central nucleus
A
contains protons and neutrons
5
Q
electron shells
A
contains electrons
6
Q
protons
A
- +1 charge
- relative mass of 1
7
Q
neutron
A
- 0 charge
- relative mass of 1
8
Q
electron
A
- charge of -1
- very small relative mass
9
Q
mass number
A
the number of protons and neutrons in the nucleus
10
Q
atomic number
A
the number of protons in the atom
proton number = electron number
11
Q
isotopes
A
atoms of the same element with the same number of protons but different number of neutrons
12
Q
pre 1900 atom
A
- tiny solid spheres that could not be divided
- John Dalton said this solid sphere made up the different elements
13
Q
1897 plum pudding atom
A
- ball of positive charge with negative electrons embedded in it
- JJ Thompson’s experiments showed an atom must contain small negative charges (electrons are discovered)
14
Q
1909 nuclear model
A
- positively charge nucleus at the centre surrounded by negative electrons
- proved by alpha particle experiment
15
Q
1913 Bohr model
A
- electrons orbit the nucleus a specific distances
- Bohr proposed electrons orbited in shells
