Topic 1: The Atom

Dalton’s Model

• Elements are made of Atoms

• Atoms of an element are the same

• Compounds are formed from combinations of atoms

Rutherford Experiment

• Bombarbed gold foil with alpha particles. Showed atoms were mostly empty space with small, dense positively charged nucleus

Bohr Model

• Small, Dense, positively charged nucleus surrounded by electrons in circular orbits

Wave Mechanical Model

• Small dense, nucleus

• Positively charged

• Surrounded by electrons moving in electron cloud

• “Orbitals” are areas where an electron with a certain amount of energy is most likely to be found”

• The # of protons are equal the # of electrons

• Each electron in an atom has its own distinct amount of energy

• Electrons fill in energy levels and orbitals starting with the one that requires the least energy, valence electrons require the most energy

• When the electron gains a specific amount of energy, it moves to a higher orbital and is in the ‘excited state’

• When an electron returns from a higher energy state to a lower energy state, it emits a specific amount of energy, usually in the form of light