Equal to the number of protons, numerical identity of an element

• boiling point

• atomic number

• melting point

• atomic mass

The average mass of atoms of an element, calculated using the abundance of isotopes in a naturally-occurring element, indicates the "size" of an atom.

• atomic number

• atomic mass

• boiling point

• melting point

Smallest part of an element that is still the same substance, constructed of negatively charged electrons orbiting a positively charged nucleus

• atom

• proton

• electron

• neutron

Tags

NGSS.MS-PS1-1

Positively charged "center", containing protons and neutrons

• nucleus

• anion

• particles

• molecule

Tags

NGSS.MS-PS1-1

Positive charge, found in nucleus, responsible for the identity of an element

• protons

• electrons

• neutrons

• cation

Neutral charge, found inside nucleus, has the most mass of all the subatomic particles

• neutrons

• proton

• electron

• anion

Negative charge, found in "electron cloud" outside nucleus, has the least amount of mass of all the subatomic particles

• electrons

• proton

• neutron

• cation

Tags

NGSS.MS-PS2-3

The number of electrons present in the outer ring or energy level in an atom

• valence electron

• group number

• family number

• energy level

Fixed paths or orbits that surround the nucleus where electrons are found (2 electrons on 1st, 8 electrons on 2nd, 18 electrons on 3rd)

• energy levels

• valence electrons

• group number

• family number

Chemical elements in order of increasing atomic number

• periodic table

• energy levels

• periods

• family/group