1
Q
What is an atom?
A
The smallest part of an element that can exist.
2
Q
What is a molecule?
A
Two or more atoms chemically bonded.
3
Q
What are the three sub-atomic particles?
A
Proton: Charge +1, mass 1, in nucleus.
Neutron: Charge 0, mass 1, in nucleus.
Electron: Charge −1, mass ~0, orbits nucleus.
4
Q
What is the atomic number?
A
The number of protons in an atom.
5
Q
What is the mass number?
A
The total number of protons + neutrons.
6
Q
What is an isotope?
A
Atoms of the same element with the same number of protons but different numbers of neutrons.
7
Q
What is relative atomic mass (Ar)?
A
The weighted average of all isotopes of an element compared with carbon-12.
8
Q
How is Ar calculated from isotopic abundances?
A
Ar = (Σ (isotopic mass × abundance)) ÷ 100
