Chemistry vocabulary

3. The number written slightly below and to the right of a chemical symbol that shows how many atoms of an element are in a compound.
6. A substance made up of two or more different types of atoms bonded together.
7. An atom of one element that has a different number of neutrons than another atom of the same element.
10. A negatively charged particle located outside of an atom’s nucleus about 2000 times smaller than either a proton or neutron.
12. number The total number of protons in an atom’s nucleus.
13. A combination of two or more substances that do not combine chemically, but remain the same individual substances.
14. The number before a chemical formula indicating how many molecules are involved in a chemical reaction.
15. change A usually reversible change in the physical properties of a substance, as size and shape.
18. of conservation of mass A scientific law stating that during a chemical reaction, matter is not created nor destroyed.
19. A substance that is present at the beginning of a chemical reaction, takes part in the reaction, and is changed into a new substance.
21. A substance that is not uniform throughout.
22. A group of atoms that are held together by covalent bonds so that they move together.
23. A neutral particle located in an atom’s nucleus.

1. A positively charged particle located in an atom’s nucleus.
2. A substance formed by a chemical reaction; made by the rearrangement of atoms and bonds in reactants.
4. mass number The total number of protons and neutrons in an atom’s nucleus.
5. A substance that cannot be broken down into a simpler substance by ordinary chemical changes.
7. An atom of group of atoms that has a positive or negative electric charge; forms by gaining or losing electrons.
8. A solid substance that forms as a result of a chemical reaction between chemicals in two liquids.
9. A substance that increases the rate of a chemical reaction but is not consumed by the reaction.
11. A substance that is evenly spread throughout. Particles not distinguishable.
16. a vertical column in the periodic table of the elements that have similar properties.
17. a horizontal row in the periodic table of the elements that have varying properties.
20. change A change of one substance into another substance.