1.
3 parts of an atom: proton, neutron, electrons
2.
4 kinds of chemical reactions: synthesis, decomposition, single replacement, double replacement
3.
acids: form hydrogen ions (H+) when they are dissolved in water. The strength of the acid depends on the number of hydrogen ions it forms. Have a sour taste.
4.
akjakus: bases that dissolve in water
5.
atom: the smallest piece of an element that can be recognized as that element
6.
atomic mass: the number of protons plus the number of neutrons in the nucleus
7.
atomic number: the number of protons in the nucleus, identifying number of an element
8.
atomic theory: what scientist think about atoms because atoms are so small they cannot actually be seen
9.
bases: form hydroxide ions (OH-) when they are dissolved in water. The strength of the base depends on the number of hydroxide ions if forms. Have a bitter taste and feel slippery.
10.
Bohr Model: 
11.
categories of a periodic table: group of elements that possess similar chemical properties and react similarly with other elements
12.
chemical change or reaction: when an atom joins a different type of atom
example: hydrogen and oxygen combine to form water (H2O), sodium and chloride combine to for sodium chloride (NaCl) commonly known as salt
13.
chemical formula: chemical symbols and numbers to abbreviate the name of a compound. Example: CO2 carbon dioxide this tells us the compound has 1 carbon atom and 2 oxygen atoms.
14.
chemical symbols: abbreviations for the names of the elements
15.
chemistry: the study of matter--what it is make of, what its usual characteristics are, and how it reacts with other matter.
16.
closed: when an atom's outermost shell is completely filled, the atom is stable
17.
compounds: what is formed in a chemical change or reaction as different types of atoms combine
18.
corrosive acids: can dissolve metals. Sulfuric acid
19.
covalent bond: bond occurring when atoms share pours of electrons therefore filling the outer shells of both atoms. gasses and liquids are most likely to contain these bonds
20.
decomposition reaction: break down complex compounds into two for more simpler compounds. Example: when our bodies break down sugar into water and carbon dioxide
21.
Demitri Mendeleev: Russian chemist who came up with a way to organize all of the elements known at that time
22.
double replacement reaction: two elements switch places
23.
electrons: negatively charged particles that travel around the nucleus
24.
elements: substances containing only one kind of atom
example: gold, silver, oxygen
25.
groups on a periodic table: a vertical column of the table
they have the same number of electrons in their outer shell
26.
hydrochloric acid: produced by the stomach to digest food
27.
indicators: substances that change color when exposed to acid or base solutions
28.
ion: an atom that has gained or lost electrons therefore the number of electrons does not equal the number of protons
29.
ionic bonds: when positively and negatively charged ions attract each other
30.
Litmus paper: paper that has been treated with an indicator substance mace from lichens
31.
matter: anything that takes up space and has mass
32.
molecule: group of atoms joined together
33.
negative ion: has gained electrons and has more electrons then protons
34.
neutral: solutions with a pH of 7 such as pure water
35.
neutralize: when an acid and a base come into contact with each other. The chemical reaction produces salt and water
36.
neutron: uncharged particles in the nucleus
37.
Niels Bohr: devised a model of an atom based on the idea that electrons move in shells
38.
noble gasses: noble gasses are made up of stable atoms and are unlikely to form compounds
39.
nucleus: center section of an atom made up of protons and neutrons
40.
particle accelerators: special machines that smash atoms into smaller particles example:quarks, leptons, mesons, pions, gravitons
41.
periodic table of the elements: classification system of elements formulated by Demitri Mendeleev
42.
periods on a periodic table: a horizontal row of the table
they have the same number of shells
43.
pH scale: "the power of hydrogen"
a scale used to determine the concentration of an acid or base in a solution.
The scale is numbered 0-14 where acids are 0-6.9 and bases are 7.1-14.
44.
positive ion: has given up electrons and has more protons than electrons
45.
proton: positively charged particles in nucleus
46.
salt: an ionic compound that contains positive ions from a base and negative ions from an acid
47.
shell: the average distance of the electrons from the nucleus
48.
shells are in layers: the first shell around the nucleus can hold 2 elections, the second shell can hold 8 electrons, each can hold more and more electrons
49.
simgle replacement reactions: one element replaces another
50.
square in periodic table: 
contains name of element (carbon), chemical symbol (C), atomic number (6), and it atomic mass (12.0107)
51.
synthesis reaction: when molecules combine to form new substances
CO2(carbon dioxide) + H2O(water) = H2CO3(carbonic acid)
52.
two types of bonds: covanlent, ionic
