1.Matter is anything that occupies space and has mass.
2.The potential to do work is called energy.
3.Electrons move around the nucleus of an atom in paths that are usually called shells.
4.The nucleus of an atom is made up of particles called protons and neutrons.
5.Atoms differ from one another only in the number of electrons and protons.
6.The number of protons in the nucleus of an atom is known as the atomic number of that atom.
7.When all the atoms within a substance are alike, the substance is called an element.
8.Common examples of elements are copper, iron and carbon.
9.Different elements can combine to form a substance called a compound.
10.The electrons in the outermost shell of an atom are called valence electrons.
11.Electrons have negative charges. Protons have positive charges.
12.An electrically neutral atom is one that has the same number of protons and electrons.
13.The energy level of an electron is related to the distance of the electron’s shell from the nucleus of an atom.
14.If a neutral atom gains electrons, it becomes a negative ion.
15.If a neutral atom loses electrons, it becomes a positive ion.
16.Ions with unlike electric charges attract each other. Ions with like electric charges repel each other.
17.The process by which atoms either gain or lose electrons is called ionization.
18.A simple way of generating an electric charge is by friction.
19.In static electricity, there is no movement of electrons between two charged objects.
20.Every charged object is surrounded by an electric field.
