subatomic particles

relative electrical charges of subatomic particles

proton +1

electron -1

neutron 0

why don’t atoms have an overall charge

In an atom, the number of electrons is equal to the number of protons in the nucleus

what do atoms of the same element have in common

the same amount of protons

what is radius of atom

having a radius of about 0.1 nm (1 x 10-10 m).

what is the radius of nucleus

The radius of a nucleus is less than 1/10 000 of that of the atom (about 1 x 10-14 m).

where is most of mass in the atom

Almost all of the mass of an atom is in the nucleus.

relative mass of subatomic particles

proton 1

neutron 1

electron very small

what makes the mass number

The sum of the protons and neutrons in an atom is its mass number.

isotope

Atoms of the same element with different numbers of neutrons but same number of protons and electrons

what is the relative atomic mass of an element

is an average value that takes account of the abundance of the isotopes of the element

formula for relative atomic mass

which shells do electrons occupy first

the lowest available energy levels