chem h sem 1 final

milli

1/1000

centi

1/100

kilo

x1000

micro

1/1000000

filtration

a technique that uses a porous barrier to separate a solid from a liquid

distillation

homogenous mixture (boiling salt water)

column chromatography

dissolved into solvent, each component is collected as it reaches bottom of column

physical change

changes physical appearance but not composition

chemical change

substance is transformed into a different substance chemically

intensive physical property

does not depend on the amount of substance (density, looks, properties)

extensive physical property

depends on amount of sample (mass, volume)

why is glassware precise?

made with more frequent and tight graduations allowing for more accurate and fine measurements

Dalton's Atomic Theory

1) all atoms of an element are identical [false]
2) atoms are smallest component of matter - can't be divided [false]
3) atoms combine in fixed ratios to form compounds
4) law of conservation of mass

law of conservation of mass

the law that states that mass cannot be created or destroyed in ordinary chemical and physical changes

law of constant composition

in a given compound, the relative numbers and kinds of atoms are constant

law of multiple proportions

If two elements A and B combine to form more than one compound, the masses of B that can combine with a given mass of A are in the ratio of small whole numbers

Thomson's Model

Plum pudding model - cathode ray tube where he used electric and magnetic fields to study the behavior of cathode rays (electrons). By balancing the fields, he showed that electrons are negatively charged particles. (electrons are embedded in a positively charged sphere)

Rutherford's experiment

Gold foil experiment - shooting alpha particles at a thin sheet of gold. Most passed through, but some were deflected, leading him to propose the nuclear model of the atom. Concluded that atoms have a small, dense, and positively charged nucleus that has electrons moving in the empty space around it.

atomic number

the number of protons in the nucleus of an atom

mass number

the sum of the number of neutrons and protons in an atomic nucleus

order of position of elements

alkali metals, alkali earth metals, transition metals, metals, nonmetals, chalcogens, halogens, noble gases

elements with roman numeral

Pb, Sn, Sb, Bi

Elements with charges

Ag: +1, Cd: +2, Zn:+2

molecular vs empirical formulas

molecular - chemical formulas that indicate actual number of atoms in a molecule, empirical: chemical formulas that only give the relative number of atoms of each type of molecule

Beta minus decay

A type of decay in which an unstable nucleus of an atom emits a beta-minus particle (an electron) and an antineutrino. 0/-1e

Beta-plus decay

A type of decay in which an unstable nucleus of an atom emits a beta-plus particle (a positron) and a neutrino. 0/1e

Alpha decay

A nuclear reaction in which an atom emits an alpha particle consisting of two protons and two neutrons. This increases the atomic number by 2 and the mass number by 4. 4/2He

Avogadro's number

6.022 x 10^23. The number of particles in exactly one mole of a pure substance

stoichiometry (avogadros)

atoms/molecules -> moles, moles of ions

stoichiometry (atomic/molar mass)

moles -> grams

empirical formula calculations

1. Assume 100 grams if only percentages are given
2.Convert % to grams
Ex: 24.5% Na = 24.5g Na
3. Multiply grams by 1 mol/molar mass
4. Divide by smallest number and round

percent error

(observed - true)/true x 100%

percent yield

actual yield/theoretical yield x 100%

How to assign oxidation numbers

-The oxidation number of a free element is zero,

- The oxidation number for a monatomic ion is equal to the charge of the ion. For example the oxidation numbers for Na+, Cu^2+, Fe^3+ Cl^= and N^3- are 1+, 2+, 3+, 1- and 3-

-The oxidation number of each Group IA element in a compound is +1

-The oxidation number of each Group IIA elements in a compound is 2+

-The oxidation number of each group VIIA element in a compound is -1, except when combined with an element of higher electronegativity. For example in HCl, the oxidation number of Cl is -1; in HOCl, however the oxidation number of Cl is +1

-Oxygen has oxidation number of -2, exception being peroxide O2^2- which is -1, and more electronegative elements, such as OF2 in which oxygen has a +2 charge.

-The oxidation number of hydrogen is usually +1
Hydrogen is +1 in HCl but -1 in NaH

molarity formula

moles of solute/liters of solution

naming acids

ate-ic
ite-ous

naming ionic compounds

The name of the metal comes first, followed by the name of the nonmetal, changing the nonmetal's ending to "ide".

naming molecular compounds

mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca

mass spectrometry

an experimental method of determining the precise mass and relative abundance of isotopes in a given sample using an instrument called a mass spectrometer

look over labs

Chemistry Lab Techniques
Phys and Chem effects lab
Glassware lab activity
percent comp of a hydrate
MgO
double replacement
CU Later
Acid Base titration

dilution and solution stoichiometry

practice

acid =

nonmetal oxide + H2O

Metal Chlorate =

metal chloride + O2

Metal Hydroxide =

metal oxide + H2O

metal carbonate =

metal oxide + CO2

combustion

CxHy + O2 --> CO2 + H2O

strong electrolytes

substances that completely dissociate into ions when they dissolve in water

weak electrolytes

weak acids and weak bases

nonelectrolytes

solutions made by molecules that dissolve in water, but do not dissociate; do not conduct electricity

diatomic

HOFBrINCl

limiting/excess reactants

1) balance reaction
2) divide # of moles by coeficcients
3) smallest answer is limiting, other is excess