| A | B |
|---|
| atom | a very small particle that makes up most kinds of matter and consists of smaller parts called protons, neutrons and electrons. |
| atomic mass | average mass of an atom of an element. |
| atomic number | number of protons in the nucleus of each atom of an element. |
| compound | a substance prouced when elements combine and whose properties are different from each of the elements in it. |
| electron | invisible, negatively charged particle located in a cloudlike formation tha surrounds the nucleus of an atom. |
| element | natural or synthetic material that cannot be broken down into simpler materials by ordinary means. |
| isotopes | tow or more atoms of the same element that hey have different numbers of neutrons in their nuclei. |
| Law of Conversation of Matter | states that matter cannot be created or destroyed but only changes its form. |
| mass number | sum of the number of protons and neutrons in the nucleus of atoms. |
| matter | anything that has mass and takes up space and is made up of different atoms. |
| metal | element that is malleable, ductile, a good conductor of electricity and generally has a shiny or metallic luster. |
| metalloid | element that has characteristics of both metals and nonmetals and is a solid at room temperature. |
| mixture | a combination of compounds and elements that has not formed a new substance and whose proportions can be changed without changing the mixtures. |
| neutron | an uncharged particle located in the nucleus of an atom. |
| nonmetals | elements that are usually gases or brittle solids and poor conductors of electricity and heat. |
| nucleus | positively charged, central part of an atom. |
| proton | positively charged particle located in the nucleus of an atom and that is counted to identify the atomic number. |
| substance | matter that has the same composition and properties throughout. |
