Atomic Structure Flashcards
Define atomic number
The total number of protons in an atom
Define mass number
The total number of protons and neutrons in an atom
Define element
A substance that consists of a single type of atom which cannot be split into anything simpler by chemical means
Define compound
Is two or more different elements chemically combined
Ions
Cations
Anions
Atoms with electric charges
Atoms with positive charge
Atoms with negative charge
Isotopes
Atoms of an element with the same atomic number but a different mass number indicating a different number of neutrons
Draw an atom
- nucleus
- orbiting electrons
- protons
- neutrons
What was the Plum Pudding model? (2)
- The 1897 ‘Plum Pudding’ model of J.J Thomson
- stated that the negative electrons were embedded in a positive sphere (like the raisins in a plum pudding).
Who discovered the electron?
J J Thomson
Who discovered the nucleus?
Ernest Rutherford
What part of the atom did James Chadwick discover in 1932 ?
Neutrons
Who discovered the proton?
Ernest Rutherford
In 1808 John Dalton published his Atomic Theory. What did he state?
Dalton stated “all elements are made up of small invisible particles called atoms”
Give the relative mass, relative charge and position of a proton, neutrons and electron
Proton - relative mass: 1
Relative charge: +1
Position: nucleus
Neutron - relative mass
Relative charge: 0
Position: nucleus
Electron - relative mass 1/1840
Relative charge: -1
Position: shell
Calculate the relative atomic mass of chlorine
Average mass number = (75x35)+(25x37)
100
= 35.5
Who discovered the neutron?
James Chadwick
Who do atoms have no charge ?
Number of electrons equals the no. of protons and they cancel each other out
What did Ernest Rutherford revise J.J Thompson’s model to ?
To the model which has electrons orbiting a positive nucleus
What is today’s model of the atom ? (2)
- Central nucleus - containing positive protons and neutral charge neutrons which make up most of the mass
- Orbiting around the nucleus in shells are negatively charged electrons
How to work out number of neutrons
Mass number - Atomic number
(protons + neutrons) - (protons=electrons)
so neutrons = protons - electrons
Radius of an atom and nucleus
0.1nm
The nucleus is less than 1/10000 of that of the atom
Isotope Definition
Isotopes are atoms of an element with the same atomic number but a different mass number indicating a different number of neutrons
