The atomic number of Au is 79 and the mass number is 197. What does this tell you about the gold atom?

Sodium is an example of _______________________.

An electron is the lightest subatomic particle, equivalent to 1/1800th of a proton.

Copper reacts with sulfur dioxide to form copper sulfide and oxygen gas. The reactants for this reaction are:

A phosphorus atom has an atomic number of 15. How many electrons does it have in its third (outermost) shell?

John Joseph Thompson passed an electron beam (shown as the green line in the diagram) through a pair of electrodes.

He found that the electron beam shifted towards the positive electrode.

Given that like charges repel each other and opposite charges attract, what Thompson could conclude about the charge of the electrons?

Atoms are always electrically neutral because they have the same number of protons and electrons.

Negative ions (anions) form when an atom gains electrons. They have a negative charge equal to the number of electrons gained.

Positive ions (cations) form when an atom loses electrons. They have a positive charge equal to the number of electrons lost.

Use this information to determine which of the images represent an ion with a charge of ^-2.

The correct chemical formula for Calcium Oxide is CaO

A physical change, such as a state change or dissolving, does not create a new substance

Mass is not conserved during a chemical reaction

The electrons in the outermost energy level of the atom are called valence electrons.