| A | B |
|---|
| proton | part of nucleus, + charge |
| neutron | part of nucleus, no electric charge |
| electron | moves around nucleus; negative charge |
| atomic nucleus | center of atom; made up of proton and neutrons |
| electron shells | surround nucleus - electrons assigned to different levels |
| atomic weight | equals sum of protons and neutrons in nucleus |
| atomic number | equals number and protons in nucleus |
| inert gas | Group O of the periodic table, including helium, neon, argon, krypton, xenon, and radon |
| ions | atom with an electric charge |
| isotopes | atoms of same element that have different numbers of neutrons in nuclei |
| ionic bond | A chemical bond between two ions with opposite charges, |
| covalent bond | sharing of a pair of electrons by two atoms |
| pH scale | scale used to describe level of acidic and basic - measure the # of ions |
| population explosion | large increase in population of species due to rapid increase in birth rate or sharply reduced death rate or both |
| population pyramids | graph that shows population by age in certain countries |
| developed countries | countries that have good economic resources;good tech, medicine - land, high resources, cultural benefits. education, health care, moderate climate |
| undeveloped countries | country w weak economic structure, poor sanitation, high death rates |
| fossil fuels | coal,oil |
| herbicides | poison used to kill plants (weeds) |
| pesticides | poison used to kill bugs |
| fertilizers | used to help plants grown |
| sanitary landfill | waste disposal area that is excavated, lined w plastic, concrete or clay and filled w layers of waste or dirt |
| leaching | occurs when soil materials dissolved in water seep down into soil |
| hazardous waste | waste that is dangerous to organism because it is poisonous, cancer causing or radioactive |
| carrying capacity | largest number of people Earth can hold |
