Atomic number

Atomic number is the number of protons in the nucleus

Articles that Atomic number Appeared in...

The Origins of the Periodic Table

The origins on the periodic table begin with the work of John Newlands and Dimitri Mendeleev.

Atomic Number of the Elements

The atomic number of the elements provides information on the number of protons in the nucleus.

Atomic Mass of the Elements

Atomic mass refers to the mass of both the protons and neutrons and is always the larger of the two represented in the periodic table.

Isotopes of Elements

Isotopes are elements with different numbers of neutrons in the nucleus but the same number of protons.

Why are There Gaps in the Periodic Table?

Gaps in the periodic table were first used by Dimtri Mendeleev when he could not find an element to fit the patterns of the groups and periods he was using. Mendeleev knew there would be undiscovered elements so used these gaps to prompt other scientists to start looking for them.

The Structure and Meaning of the Periodic Table: Groups

Groups in the periodic table are the columns where elements with similar properties are found grouped together.

The Lanthanides of the Expanded Periodic Table

The lanthanides are a series of chemicals in the expanded periodic table that have an expanded number of orbitals beyond that of the transition metals. The lanthanides are mostly soft metals with their hardness increasing across the period. Whilst they are metals and can conduct electricity the lanthanides have a relatively high resistivity.