1. principles of chemisty

What are the three states of matter?

Solid, liquids and gas

Describe the particles in a solid, liquid and gas

• Solid: particles are closely packed together and vibrate in fixed positions

• Liquid: particles are closely packed together but can move past each other

• Gas: particles are far apart and move freely in all directions

What is an element?

An element is a pure substance made of only one type of atom

What is a compound?

A compound is a substance made when two or more different elements are chemically bonded together

What is a mixture?

A mixture is two or more substances that are not chemically bonded together

What are protons, neutrons and electrons?

They are the three subatomic particles that make up an atom

What are the charges and locations of protons, neutrons and electrons?

• protons: positive (+1), found in the necleus

• Neutrons: neutral (0), found in the necleus

• Electrons: negative (-1), found in shells around the necleus

What is the atomic number ?

The atomic number is the number of protons in an atom

What is the mass number?

The mass number is the total number of protons and neutrons in an atom

What is isotope?

An isotope is an atom of the same element with the same number of protons but a different number of neutrons

How are elements arranged in the periodic table?

Events are arranged in order of increasing atomic number

What is a group and what is a period ?

• group: a vertical column of elements with similar properties

• Period: a horizontal row of elements

What is a chemical formula?

A chemical formula shows the types and numbers of atoms in a substance

Why must chemical equations be balanced?

Because atoms cannot be created or destroyed, so there must be the same number of each type of atom on both sides of the equation

What is ionic bonding?

Ionic bonding is a bond formed when two non metal atoms share pairs of electrons to achieve a full outer shell