Hydrogen 1p+, 1e _ Helium 2p+, 2e _ electron proton neutron The Atom

Sub Atomic Particles NameMassChargeLocation Proton1 AMU + 1Nucleus Neutron1 AMU N/ANucleus ElectronN/AElectron Cloud

Carbon 6p+, 6e _ Oxygen 8p+, 8e _

Molecules Chemical bonds hold together two or more atoms of the same or different elements –Ex: Nitrogen gas: N2 Chemical bond: a union between the electron clouds of two atoms Molecules of compounds-elements in proportions never vary.

SODIUM ATOM 11 p + 11 e - electron transfer CHLORINE ATOM 17 p + 17 e - SODIUM ION 11 p + 10 e - CHLORINE ION 17 p + 18 e -

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Molecular Hydrogen (H 2 ) Molecular Oxygen (O 2 ) Water (H 2 O)

Covalent bonding Click to view animation.

Water moleculeAmmonia molecule Hydrogen bond

H H O Slight negative charge at this end Slight positive charge at this end No overall charge

Multiple H bonds holding two molecules together

Liquid water Ice

In-text Figure Page 20

Na + Cl – – – – – – – – – – – –

cohesion evaporation