Good Stuff to Know

The Law of Definite Proportions

a specific chemical compound always contains the exact same elements in the same fixed proportions by mass, regardless of the source or how the compound was prepared

The Law of Multiple Proportions

when two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other are in a ratio of simple whole numbers

Octet rule

atoms tend to gain, lose, or share electrons until they have a full outer shell of eight valence electrons

Metals, nonmetals, and metalloids

metals: shiny, conductive, malleable

nonmetals: dull, insulative, brittle

metalloids: properties of both

predictable periodic property

A predictable periodic property (periodic trend) is a characteristic of elements that repeats in a regular, rhythmic pattern (periodicity) as you move across or down the periodic table.

How is the periodic table arranged to display chemical properties?

The periodic table is arranged by increasing atomic number (number of protons).

What physical properties can be predicted using the periodic table?

Atomic radius, electronegativity, ionization energy, metallic character, melting and boiling points