C1.2 Flashcards
What is an atom?
The smallest particle of an element that still has its chemical properties
What is a molecule?
2 or more atoms joined together i.e by bonds
How big is an atom
1 x 10^-10 m
How big is an atomic nucleus
1 x 10^-15 m
Describe the relative mass and charge of
Protons
Neutrons
Electrons
P - 1, +1
N - 1, 0
E - 0.0005 (negligible), -1
What is the mass number?
The number of protons and neutrons
What is atomic number?
Number of protons
What is an isotope
Atoms of the same element with the same number of p and e but different numbers of neutrons, also changing the mass
What are ions?
Charged particles caused by the loss or gain of electrons
Lose electrons = positive charge and vice versa
What did Dalton suggest?
Atoms were indivisible and solid spheres
All atoms of an element are identical,different elements have different atoms
What did Thomson do?
His cathode experiment proved the existence of electrons in an atom.
He said an atom was positive mass with electrons embedded inside
What did Rutherford do?
His gold foil experiment suggested that an atom was mostly empty space with a small dense positive mass,and electrons orbited that
What did Bohr do?
He realised that electron orbit meant the crashing of electrons into the nucleus, so he suggested that electrons sat in energy levels around the nucleus.
