C1.2 Flashcards
What is an atom?
An atom is the smallest particle of an element that still has chemical properties.
What is a molecule?
A molecule is made from two or more atoms joined together. They are joined by attractive forces called chemical bonds.
How big is an atom?
The size of an atom is given by its atomic radius which is half its diameter.
What is a bond length?
A bond length is the distance between the centres of two joined atoms.
What is inside of an atom?
Protons and neutrons join together in the nucleus which is in the centre. Electrons surround the nucleus in the shells.
What is the relative mass of protons, neutrons and electrons?
Proton = 1
Neutron = 1
Electron = 0.0005
What are the relative charges of protons, neutrons and electrons?
Proton = +1
Neutron = 0
Electron = -1
What is a mass number?
A mass number is the total number of protons and neutrons.
What is an isotope?
An isotope is an element with the same number of protons and electrons but a different number of neutrons.
What are ions?
Ions are charged particles. They are formed when atoms lose or gain electrons.
What did Dalton do?
Dalton suggested that all atoms of an element are identical. Different elements contain different types of atoms.
What did Thomson do?
Thomson suggested atoms contain electrons. Atoms are neutral overall.
What did Rutherford do?
Rutherford suggested that an atom has a positively charged nucleus containing most of its mass. He also suggested electrons orbit the nucleus.
What did Bohr do?
Bohr showed that electrons occupy fixed energy levels, or shells, around the nucleus.
