An atom becomes a positive ion by gaining an electron.

Niels Bohr’s model of the hydrogen atom

In a chemical equation, the reactants are found on the left side of the arrow.

Ionic bonds occur between atoms from adjacent groups.

Atoms from an element in group VA are allowed to react with atoms from an element in group VIIIA. What type of compound is likely to form?

How many molecules are in an 8.0-g sample of oxygen gas, ?

Heisenberg’s uncertainty principle says that you cannot know the momentum or the position of an electron exactly.

If you want to know the number of protons in an atom of a given element, you must look up its

In the notation , the 4 refers to the

When balancing a chemical equation, you need to change subscripts to make the number of atoms of an element the same on both sides of the equation.