Chemistry vocab

1. change a change of one substance into another substance
3. a substance that is present at the beginning of a chemical reaction, takes part in the reaction, and is changed into a new substance
4. a group of atoms that are held together by covalent bonds so that they move together
9. a substance that is evenly spread throughout. Particles not distinguishable.
12. a horizontal row in the periodic table of the elements that have varying properties
13. an atom of one element that has a different number of neutrons than another atom of the same element
15. a neutral part, located in an atoms nucleus
16. an atom of group of atoms that has a positive or negative electric charge, forms by gaining or losing electrons
19. a solid substance, that forms as a result of a chemical reaction between chemicals in two liquids
20. a vertical column in the periodic table of the elements that have similar properties
21. a substance that increases the rate of a chemical reaction, but is not consumed by the reaction
22. the number written slightly below into the rate of a chemical symbol that shows how many atoms of an element are in a compound

2. a combination of two or more substances that do not combine chemically, but remain the same individual substances
5. a substance made up of two or more different types of atoms bonded together
6. a substance that cannot be broken down into a simpler substances by ordinary chemical changes
7. a negatively charged particle located outside of an atoms nucleus about 2000 times smaller than either a proton or neutron
8. of positively charged particle, located in an atoms nucleus
10. a substance that is not uniform throughout
11. the number before a chemical formula indicating how many molecules are involved in a chemical reaction
12. change a usually reversible change in the physical properties of a substance, as size and shape
14. number the total number of protons in an atoms nucleus
17. a substance formed by a chemical reaction, made by the rearrangement of atoms in bonds and reactants
18. mass number the total number of protons and neutrons in an atoms nucleus