Atomic bonding The games atoms play with electrons. Also the reason oil & water do not mix.

Bonding w/ Aliens What happens to the fingers of the aliens as you move across a period? The number of fingers increases by 1. What happens to the aliens as you move down a group? The number of hairs (legs) increases by 1. How are these 2 things analogous to the periodic table?

Periodic table & valence electrons What do the numbers of the periods represent? The number of energy levels in the atom. What do the numbers of the groups represent? The number of electrons in the highest energy level. Valence electron – electron in an atoms highest energy level Valence electrons determine the reactivity & bonding of an atom. The most reactive elements have the fewest valence electrons.

Atoms & stability (Expectation 1) Which elements are stable & do not react with other elements? Noble gases Octet rule – atoms gain or lose electrons to attain a full set (8) of valence electrons. Achieving an octet allows the atom to achieve stability. Atoms form bonds to become more stable Stable atoms have a lower energy state. Analogy – standing on 2 legs versus 1

Ways to achieve the octet Atoms can lose electrons to reveal a full orbital. This results in a positive ion. Atoms can gain electrons to achieve a full orbital. This results in a negative ion.

Lewis dot structures (Expectation 2) Lewis dot structures represent the number of valence electrons in an atom and are used to determine bonding between atoms & chemical formulas. Drawing Lewis dot structures Write the element symbol. Determine the group of the element. Draw dots around the element, one on each side, until you have the same number of dots as is the group number

Why do some lose & others gain? Electronegativity – the attraction an atom has for an electron when forming bonds with other atoms. Higher electronegativity means a greater attraction.

Charges on metals & non-metals (Expectation 3) Metallic elements lose electrons & form positive ions. This is because they have a low electronegativity. Non-metallic elements gain electrons & form negative ions. This is because they have high electronegativity.