The number of protons and neutrons within the atom's nucleus.

The subatomic particle with a negative charge; located outside of the nucleus; cause all reactions in Chemistry

A material that contains only one kind of atom; found on the periodic table; represented by symbols

A pure substance whose smallest unit is made of atoms of more than one element; chemically combined; represented by formulas

A subatomic particle with no electrical charge; located within the nucleus.

Two or more substances physically combined without forming a new substance.

Anything that takes up space and has mass.

A positively charged subatomic particle located within the nucleus; identifies the atom

Atoms of the same element that have different numbers of

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The number of protons within the nucleus; represented by the letter Z

The smallest particle of an element that can exist either alone or in combination with other atoms.

Represented by element name and the mass number.

Abbreviation found on the periodic table.

The number of protons equals the number of electrons

The arrangement of elements by atomic number.