atom - makes up all matter and all substances in the universe
- can be seen indirectly w/ tech such as tunnel microscopy
- electrons - (-) charge; revolves around the nucleus
- neutrons - no charge; in the nucleus
- protons - (+) positive charge; in the nucleus; determines the atom's atomic number
- mass - amount of substance
- weight - force gravity exerts on a substance
- atomic mass - equal the combined mass of neutrons/protons; measured in daltons (6.02*10^23 daltons=1 gram)
isotopes - atoms of an element w/ different numbers of neutrons
- elements - same atomic number, same chemical properties
- radioactive isotope - isotopes that decay due to unstable nuclei; decay is constant
- half-life - time is takes 1/2 of the atoms to decay; can be used to determine age of biological material
- released subatomic particles could cause mutations in genes
electrons - determines the charge in each atom
- neutral atoms - not net charge, same number of electrons/protons
- ions - atoms in which the number of electrons is different from the number of protons
- cation - ion with positive charge
- anion - ion with negative charge
orbital - area where an electron is most likely to be found
- each can't contain over 2 electrons
- electrons determine the atom's chemical behavior because the nuclei never interact
- electrons contain potential energy based on their position
- oxidation - loss of electron
- reduction - gain of electron
- energy level - based on an electron's distance from the nucleus; different from orbitals
periodic table - developed by Dmitri Mendeleev
- elements' chemical properties repeated themselves in groups of 8
- valence electrons - electrons on the outermost energy level; basis for the atoms' chemical properties
- noble gases - elements w/ filled outer levels; are inert and nonreactive
- halogens - elements w/ 7 electrons in outer levels; extremely reactive
- octet rule - atoms tend to completely fill their outer levels
chemical bonds - connects atoms in a molecule and molecules in a compound
- ionic bonds - forms between atoms of opposite charge; exists between an ion and all oppositely charged ions in the area
- covalent bonds - forms between 2 specific atoms when electrons are shared; has no net charge or free electrons
- single bond - 1 electron is shared
- double bond - 2 electrons are shared
- triple bond - 3 electrons are shared
- structural formulas - shows elements in a compound and their bonds
- molecular formulas - shows only the elements in a compound
- atoms can form many covalent bonds (ex. carbon)
- chemical reaction - forming/breaking of chemical bonds
- reactants - original molecules before the reaction
- products - resulting molecules after the reaction
factors influencing reactions
- higher temperature increases reaction rate
- temperature must not be so high that it destroys molecules
- more reactants exposed to each other increases reaction rate
- catalyst - substance that increases reaction rate; proteins called enzymes act as catalysts in organisms
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