The Periodic Table

The Periodic Table

• John Newlands – 1864 – law of octaves

The Periodic Table

• John Newlands – 1864 – law of octaves

• Dmitri Mendeleeve – first periodic table predicted missing Atoms

The Periodic Table

The Periodic TableArranged according to electronic configuration and

by increasing atomic number.

The Periodic Table

Representations in chemical equations

Metals – represented in their empirical formula Fe, Cu…..

Non Metals – no set rule – based on most common form C, P4

If diatomic

(H2, N2, O2, F2, Cl2, Br2, I2)

Sulfer - is S8 but usually used as SMetaloids – like metals use empirical

formula B, Si, Ge

Removal of Electrons

• Mn2+ has config of [Ar] 3d5

NOT [Ar] 4s23d3

• Electron filling does not predict the order of electron removal in transition metals

Atomic Radius

Size of atom – the volume that encompasses 90 % of the electron density.

Atomic Radius – one half the distance between the two nuclei in two adjacent atoms.

Determined by x-ray diffraction.