Atomic Number, Mass and Mass Number- Subatomic Particles

Today we learned about the different characteristics of modern atoms.

Recall that an atom is made up of 3 types  of subatomic particles.

The Proton
Has a charge of +1.
Has a mass of 1.
Location: Nucleus

The Electron
Has a charge of -1
Has a mass of (not equal to) zero
Location: Energy shells surrounding nucleus

The Neutron
Has a charge of 0
Mass of >1.
Location: Nucleus

The atomic number(Z) of an element is the number of protons in its nucleus.

Atoms can form ions, which are charged atoms.
To form a negative ion(anion) electrons must be added to a neutral atom.
To form a positive ion(cation) electrons must be taken away from a neutral atom.

To find the charge of an atom: # Protons- #Electrons.

The mass number of an element is the sum of its protons and neutrons
The atomic mass is the average of masses of existing isotopes of an element.

An isotope of an element always has the same number of protons but a different number of neutrons.

How to calculate atomic mass.

Three naturally occurring isotopes with their percent abundance.

12(60%), 13(36%), 14(4%)

Calculate atomic mass.

12 x 60%= 7.2
13 x 36% = 4.68
14 x 4% = 0.56

Now add: 7.2 + 4.68 + 0.56 = 12.4.