chemistry exam

concepts, definitions, pictures - look through the book and practice problems

chemical reactions

chemical reactions

rearrange atoms to produce chemicals different from those that were originally present

ex, Mg + 2HCl —> MgCl2 + h2

word equation

a way a saying a chemical reaction using words

ex. magnesium metal is reacted with aqueous (solution) hydrochloric acid to produce aqueous magnesium chloride and hydrogen gas

formula equation

a way of showing a chemical reaction using the actual elements in the equation with one side being reactants and another being products

visualization

showing chemical equations using pictures to represent the atoms and the amount and also using different colors to differentiate between the elements

reactants

the part of the chemical equation, the original chemcals that are acting together

products

the right side of the arrow that is the new chemicals produced

s, g, l, a

solid, gas, liquid, and aqueous, are used to indicate the state of matter in a equation, sometimes this will be given to you and others will not have enough information to identify it

writing word equations to formulas

take the elements and look for key words in the equation to figure out which goes on left and right, then make sure the equation is balanced

balancing equations

to change the equation so the amount of each element is the same. to abide by the law of conservation of mass which states that matter cannot be created or destroyed

classifying chemical reactions

double replacement, single replacement, combustion, synthesis, decompostition

double replacement

when the reactants switch spots with each in the products

ab +cd = ad +bc

single replacement

works with equations with three elements, where only one reactant switches places,

ab + c = ac +b

synthesis

where the reactants come together in the products

a +b = ab

decompositions

when the react separate in the product

ab = a +b

combsution

has to have oxygen in the reactant and water and carbon dioxide in the products

__ + o2 = co2 + h2o

neutralization

has to have water and ionic compound in the products

mole

a unit of measurement to help figure out what we can’t see

avogadros number

6.02 × 10²³

atomic mass

the mass put on the bottom of the element box on the periodic table thats specific to the element and it is equal to 1 mole of that element

molar mass

the mass of the entire compound

molar volume

22.4 L = 1 mole

percent composition

the percent of each element in a compound, finding the entire mass, then find the mass of each atom individually

practice mole conversion

mass, gas, liters , molecules ( atoms, formula units)

Stoichiometry

the process of calculating amounts of reactants and products in a reaction iusing the mole ratio from a balanced equation

percent yield

a calculation of a reactions efficiency by comparing the amount of product actually generated to what is theortically possible

calculatinjg actual yield v theoretical yield

actual yield/ theoretical yield

actual

collected, generated

theoretical

calculated, expected

atomic number

number used to determine the element also the amount of protons

mass number

p + n

atomic mass

the weight of one mole of the element

john dalton

proposed the atomic theory, atoms are indivisible and indestructible, all atoms are identical in. mass (proved wrong bc of subatomic particles and isotopes), solid sphere model

based on law of conservation mass and the law of constant compostion

jj thompson

identified a negative entity within atoms (subatomic particles), cathode ray tube experiment, plum pudding model

cathode ray

deflected by negative charge, ray of light traveling in a vacuum

ernest rutherford

positive charge and mass are in a confined small area, gold foil experiment, atom is mostly empty space, nuclear model

gold foil experiment

positive charged alpha particles fired at atoms, mostly pass through undeflected, but once in a great while are deflected at great angles

niels bohr

electrons exist at specific energy levels, light emission spectra, and mathematic calculations, electrons have specific possible and energy amounts, planetary model

light emissions spectra

light patterns caused by electrons can generally be explained by mathematical computations

protons

postive, in the nucleus, mass and charge

electrons

negative, electron cloud, charge

neutrons

neutral, nucleus, mass

atom

the smallest piece of matter that has the chemical properties of the element

nuclear symbol

dmitri mendeleev

organizing the periodic table and left hols for new elements

period

horizontal on the periodic table

group

vertical on the periodic table

anion

negative ion

cation

postive ion

isotope

atoms of the same element with a different number of neutrons/different mass numbers

average atomic mass

find the sums of the isotopes and multiply the percent then add them together to the element

valence electrons

electrons on the outermost energy levels

different subshells

s, p, d ,f

s

2 e, 1 o

p

6 e, 3 o

d

10 e, 5 o

f

14 e , 7 o

s subshell endings

akali, and akaline

p subshell endings

the far right of the periodic tables

d subshell endings

transition metals

f subshell endings

lathan, actina

orbitals

where the electrons will mostly be located

aufbau

spectroscopic, electrons fill sub shells so that the total energy of atom is the minimum

hund’s rule

box and arrows, when filling the subshell, place electrons in unoccupied orbitals before pairing them up

pauli exclusion principle

two electrons that occupy the same orbital must have different spins, opposite spins

noble gas notation

the previous noble gas is used to represent the beginning configuration followed by the rest of the electrons

principle energy level

the shell or orbital in which the electron is located relative to the atom's nucleus

where the valence electrons are

octet rule

all the elements have to equal 8 using dots and bonds

single bond

2

doublebond

4

triple bond

6

lewis dot structure

drawing molecule using dots and bonds to figure out where the elements should go

ionic compound

metal + non metal

covalent compound

non metal + non metal

shared pair

two dots together on one side of an element

lone pair

one dot on one side of the element

NH4

exception

ch3cl

ionic and covalent

ionic bond

cluster of + and - , transfers electrons, overcomes ionic bonds, soluble, free-floating ions, can conduct, high stp

non polar

nonmetal - nonmetal, evenly shared electrons, insoluble, intermolecular forces, cannot conduct, very low stp

polar

non metal - non metal, share electrons unevenly, overcome intermolecular forces, soluble, cant conduct, medium/low stp

metallic

metal + metal, pool of electrons, not bonded to specific atoms, insoluble, can conduct, med/varies stp