teas science portion

proton

positive charge inside nucleus; number of protons = atomic weight

electron

negligible mass; in electron shell

valence electrons

electrons in the outermost shell; even = stable & odd = unstable

neutrons

no charge; in nucleus

electronegativity

ability of an atom to pull electrons towards itself; decreases on periodic table up to down, & increases left to right

most electronegative element

F; fluorine

uncharged atom

number of electrons = number of protons

ion

number of protons does not = number of electrons

cation

positive charge; forms when an atom loses an electron to become a more electronegative ion; number of electrons > protons

anion

negative charge; forms when atom gains electron from a less electronegative atom; number of electrons < protons

covalent bond

shares electrons; strongest type of bond

ionic bond

a type of chemical link formed when one atom gives an electron to another atom (cation & anion); Na+ - sodium

hydrogen bond

weak bond where no electrons are lost or shared; H2O

base

hydrogen<hydroxide; pH greater than 7

acid

hydrogen>hydroxide; pH less than 7

neutral

hydrogen=hydroxide; pH of 7

atomic number

protons in an element; left upper corner on periodic table

atomic mass

protons + neutrons in element; number under chemical symbol on periodic table

atomic mass - atomic number =

neutrons

isotopes

same chemical elements, but different # of neutrons

octet rule for ionic & covalent bonds

valence shell needs 8 electrons; if it is without 8 electrons, it may gain, lose, or share electrons

carbon, oxygen, nitrogen, & hydrogen mostly form…

covalent bonds

periods of periodic table

7 rows; reflects # of electron shells 1-7

groups of periodic table

vertical rows; reflects number of valence electrons

mass

amount of matter in object

volume

amount of space object occupies

density

mass divides by volume; how much matter is packed into a given space

plasma

ionized gas; ions have been stripped from atom (stars)

higher the temperature,

the more energy molecules have & the more space it takes up

the higher the pressure…

the more molecules are pushed together

example of pressure changing the form of matter

condensation; molecules of water are forced together turning gas into a liquid

sublimation

solid turning to gas

deposition

gas into a solid

balancing chemical equations

adding coefficients to an equation in order to insure there is an equal number of atoms of each element on both sides of the equation

mole

unit used to measure the amount of a substance

catalyst

speeds up a chemical reaction by lowering activation energy

endothermic reaction

absorbs heat; ex) egg absorbing heat from pan

exothermic reaction

releases heat; ex) condensation of water vapor into rain

chemical equilibrium

rate of the forward action is equal to the rate of the reverse action

dynamic equilibrium

forward & reverse reactions are occurring at the same time; ex) carbon dioxide in soda is dissolved into liquid form at the same rate as it is being converted to gas

static equilibrium

concentrations of the reactants & the products are not changing; ex) gravity is the same for all objects so the weight of the body stays the same when re positioned

activation energy

minimum amount of energy that is needed for chemical reaction

the polarity of water allows it to form…

hydrogen bonds with other molecules

cohesion

type of hydrogen bond; a similar molecule surrounding & binding to another molecule; water attracts water

adhesion

type of hydrogen bond; dissimilar molecules binding to another molecule

molarity

concentration of solute in solvent; mol/L

neutralization reaction

chemical reaction between acid & base; ex) antacid

What is an example of an exothermic reaction?

burning wood; releases heat

a student dissolved NaOH in water & the temo of the solution rises. What can be concluded?

the reaction is exothermic; releases energy as heat

what is the atomic number of an atom that has 12 protons & 12 neutrons?

12

Why are noble gases generally unreactive?

outer electron shells are full with 8 valence electrons

nitrogen gas is an extremely stable molecule because…

it forms triple covalent bonds; each nitrogen atom shares 3 pairs of electrons

describe a change that takes place when a solid turns into a liquid

particles become less ordered

what occurs in an oxidation reaction?

removal of electrons

oxidation

loss of electrons

reduction

gain of electrons

Which of the following atoms is most likely to become an anion?

Flourine - atomic # of 9

why does lemon juice slow the process of browning on an avocado?

lemon juice has a pH that inactivates the enzymes responsible for browning

if CH+] = 10^-n than

pH = n

the basic unit of life

cells

modern cell theory

cells are the smallest living unit, all living things are made up of cells, & all cells came from pre-existing cells

prokaryotes

bacteria, archea; no nucleus or membrane bound organelles; has cytoplasm, DNA, ribosomes, & cell membrane

eukaryotes

animals, fungi, protists, plants; DNA in nucleus, cytoplasm, ribosomes, cell membrane, & membrane bound organelles

endoplasmic reticulum

calcium storage, protein storage

rough ER

provides surface area for chemical reactions & metabolizes lipids

smooth ER

makes hormones, lipids, & detoxes

golgi apparatus

helps process & package proteins & lipids

vacuole

helps sequester waste in animal cells & maintains water balance in plant cells