atomic structure and calculations Flashcards
1
Q
what is a compound
A
- composed of two or more elements chemically joined
2
Q
what is an atom
A
- smallest parts of an element
3
Q
what is found in the nucleus
A
- proton: positive charge (same number as electrons)
- neutron: neutral charge
4
Q
what are electrons
A
- negative charge
- orbit the nucleus in the electron cloud
- same number of electrons as protons
5
Q
what is the mass number
A
- number of protons and neutrons in the nucleus
- known as ‘a’
- found at the top of the element
6
Q
what is the atomic number
A
- number of protons (same as the number of electrons)
- known as ‘z’
- found at the bottom of the element
7
Q
what is an isotope
A
- atoms that have the same number of protons and a different number of neutrons
- resulting in a different mass number
8
Q
what is relative atomic mass
A
- Ar: the average mass of one element
9
Q
what is relative molecular mass
A
- Mr: average mass of a compound
10
Q
what is percentage composition
A
- percentage by mass of each element in a compound
- percentage of an element = (total Ar for element / total Mr for that compound) x 100
11
Q
what is a mole
A
- 6.022 x 10^23 particles of a substance (n)
12
Q
what is molar mass
A
- the mass of one mole of a substance (M)
- units: g mol^-1)
13
Q
what is an element
A
simplest substance (cannot be broken down)
14
Q
what is atomic mass
A
-mass of one mole of atoms of an element (amu)
15
Q
what is molecular mass
A
- mass of one mole of molecules of an element or compound (amu)
