Vocab

5. A substance that is present at the beginning of a chemical reaction, takes part in the reaction, and is changed into a new substance.
6. number: The total number of protons and neutrons in an atom’s nucleus.
10. A substance made up of two or more different types of atoms bonded together.
12. 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.
13. The total number of protons in an atom’s nucleus.
14. a vertical column in the periodic table of the elements that have similar properties.
16. A substance that is not uniform throughout.
17. A neutral particle located in an atom’s nucleus.
18. An atom of group of atoms that has a positive or negative electric charge; forms by gaining or losing electrons.
21. A negatively charged particle located outside of an atom’s nucleus about 2000 times smaller than either a proton or neutron.
22. A group of atoms that are held together by covalent bonds so that they move together.
24. A combination of two or more substances that do not combine chemically, but remain the same individual substances.

1. A change of one substance into another substance.
2. A usually reversible change in the physical properties of a substance, as size and shape.
3. A substance that increases the rate of a chemical reaction but is not consumed by the reaction.
4. A scientific law stating that during a chemical reaction, matter is not created nor destroyed.
7. A negatively charged particle located outside of an atom’s nucleus about 2000 times smaller than either a proton or neutron.
8. A substance formed by a chemical reaction; made by the rearrangement of atoms and bonds in reactants.
9. A solid substance that forms as a result of a chemical reaction between chemicals in two liquids
11. A substance that is evenly spread throughout. Particles not distinguishable.
15. a horizontal row in the periodic table of the elements that have varying properties.
19. A positively charged particle located in an atom’s nucleus.
20. The number before a chemical formula indicating how many molecules are involved in a chemical reaction.
23. A substance that cannot be broken down into a simpler substance by ordinary chemical changes.