Atomic Structure and Electron Structure

Relative Atomic Mass

Average mass of one atom of an element compared with 1/12th mass of an atom of Carbon-12

RAM

An Atomic Orbital

A region within an atom that can hold up to 2 electrons with opposite spins

S and P oribtals

• S orbital- spherical

• P orbital - dumbell shape

Electron Configuration

1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²

Shorthand configuration can be written using the noble gas configuration that comes before the element e.g.

Si: 1s²2s²2p⁶3s²3p²→ [Ne] 3s²3p²

Electron Configuration Exceptions and Reasons

• Chromium: 1s²2s²2p⁶3s²3p⁶4s¹3d⁵

• Copper: 1s²2s²2p⁶3s²3p⁶4s¹3d¹⁰

Reasons: These represents more stable arrangements