Ap Chemistry Notes 1.A.1

Enduring Understanding 1.A: All matter is made of atoms. There are a limited number of types of atoms; these are the elements.

Atoms are the building blocks of all matter.

Moles allow for relating measured masses in the laboratory to the number of particles present in a sample.

1.A.1: When 2 elements combine with each other to form 2 or more compounds, the ratios of the masses are whole numbers.

The average mass of an element is always the same.

A pure sample is composed of either 1 atom or molecule. A mixture is composed of more than 1 atom or molecule.

The ratio and mass of atoms in a compound is always consistent.

The number of elements in a compound must be a whole number.

1.A.2: Chemical analysis allows us to determine the number of atoms in a substance

You can identify a substance or a substance’s purity from the amount of atoms it has.

Atoms have known masses.

There is a relationship between the mass percent of the compound and the mass percent of atoms.

The empirical formula is the lowest whole number ratio of atoms in a compound.

Two compounds with the same ratio of atoms will have the