genchem1 exam1

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define matter

anything that has both mass and volume

define composition

types and amounts of simpler substances that make up a sample of matter

define property and list/define the 4

the characteristics that give each substance a unique identity, intensive: internal properties, temp., density; extensive: external properties, mass, volume; physical: substance that shows by itself; chemical property: substance shows as it interacts with or transforms into other substances.

define energy and the 2 types

energy is the ability to do work, there is potential energy due to position of the object, and kinetic energy the movement of the object.

give the conversion of: mega

10⁶

give the conversion of: kilo

10³

give the conversion of: deci

10^-1

give the conversion of: centi

10^-2

give the conversion of: milli

10^-3

give the conversion of: micro

10^-6

give the conversion of: nano

10^-9

give the conversion of: pico

10^-12

define precision

reproducibility or how close the measurements are to each other

define accuracy

refers to how close a measurement is to the real value

what are the 2 types of errors and define them

systematic error: values ALL higher or lower than the actual value

random error: some values are higher and lower than the actual value

significant digit rule for multiplication and division

contains the same number of significant digits as there are in the measurement with the fewest significant figures

significant digit rule for addition and subtraction

the answer has the same number of decimal places as there are in the measurement with fewest decimal places

define element

simplest substance with unique physical and chemical properties, consists of only 1 atom and cannot be broken down

define molecule

structure consisting of > or = 2 atoms chemically bound together, can be molecules of an element or compound

define compound

substance with > or = 2 elements chemically combined

define mixture

group of > or = 2 elements and/or compounds physically intermingled

define heterogeneous mixture

has one or more visible boundaries between the components

define homogeneous mixture

has no visible boundaries because the components are mixed as individual atoms, ions, and/or molecules; it is also called a solution

define aqueous solutions

solutions in which water is the solvent

define material complexity

based on mass, starting material broken into samples of lower mass

what are the 3 key laws showing the existence of the atom?

law of conservation of mass, law of definite (or constant) composition, law of multiple proportions

what is the law of mass conservation?

total mass of substances does not change during a chemical reaction

what is the law of definite (or constant) composition?

no matter what the source of a compound its elements occur in the same proportion by mass

what is the law of multiple proportions?

when different numbers of atoms of elements combine, they must do so in ratios of small, whole numbers

what are the 4 parts to Dalton’s atomic theory?

1. all matter consists of atoms; tiny divisible particles of an element that cannot be created or destroyed.

2. atoms of one element cannot be converted into atoms of another element.

3. atoms of an element are identical in mass and other properties and are different from the atoms of any other element.

4. compounds result from the chemical combination of a specific ratio of atoms of different elements.

what are the 4 key experiments?

cathode ray tube experiment (JJ Thompson), rays of positive electricity (JJ Thompson), oil drop experiment (Milliken), alpha particle backscattering (Rutherford)

what did the cathode ray experiment discover?

existence of electrons, negatively charged particles in all atoms

what did the rays of positive electricity discover?

existence of positively charged subatomic particles

what did the oil drop experiment discover?

the charge on the electron and the electron mass

what did the alpha particle backscattering discover?

the nuclear model of an atom

define isotopes

atoms of an element with the same number of protons but different number of neutrons

which group has a +1 charge on the periodic table?

alkali metals

which group has a +2 charge on the periodic table?

alkaline earth metals

which group has no charge on the periodic table?

noble gases

which group has a -1 charge on the periodic table?

halogens

what are the 3 elements in the transition metals that have a fixed charge? what are their charges?

Al³⁺, Zn²⁺, Ag¹⁺

what parts of the periodic table requires no roman numerals when naming?

groups 1, 2, 18

characteristics of metals

solids (except Hg), electrically & thermally conductive, ductile and malleable, alkaline oxides, electropositive (cations)

characteristics of metalloids

solids, electrically semi-conductive, hard, amphoteric oxides, electropositive (cations)

characteristics of non-metals

solids/liquids/gases, generally insulating solids, acidic oxides, electronegative (anions)

what are ionic compounds?

metal + non-metal or metal + polyatomic ion

what are covalent compounds?

non-metal + non-metal or non-metal + metalloid

what are the factors that influence the strength of ionic bonding?

attraction increases as size decreases and increases as charge increases

define ion

a single atom or covalently bonded group of atoms that has an overall electrical charge

define polyatomic ions

consist of > or = 2 atoms covalently bonded together with a net charge

how do you name binary ionic compounds?

cation first anion second, cations remain the same or end with -ium, anions add the suffix -ide to the root of the nonmetal name

NH₄⁺

ammonium

H₃O⁺

hydronium

CH₃COO^-

acetate

OH^-

hydroxide

ClO₃^-

chlorate

ClO₂^-

chlorite

ClO^-

hypochlorite

ClO₄^-

perchlorate

NO₃^-

nitrate

MnO₄^-

permanganate

CO₃^2-

carbonate

HCO₃^-

bicarbonate

Cr₂O₇^2-

dichromate

PO₄^3-

phosphate

SO₄^2-

sulfate

how do you name binary acids?

prefix hydro- + anion nonmetal root + suffix -ic + the word acid

how do you name oxoacids?

-ate in the anion becomes -ic in the acid, -ite in the anion becomes -ous in the acid, the oxoanion prefixes hypo- and per- are retained

how do you name binary covalent compounds?

the element with the lower group number or period is first in the name remaining unchanged, the element second is named using the root with suffix -ide.

what are the numerical prefixes for hydrates and binary covalent compounds?

1-mono, 2-di, 3-tri, 4-tetra, 5-penta, 6-hexa, 7-hepta, 8-octa, 9-nona, 10-deca

HCl

hydrochloric acid

Cu₂O

copper(I) oxide

Ni(OH)₂

nickel(II) hydroxide

BrO₄^-

perbromate

HBrO₄

perbromic acid

define mole

the amount of substance that contains the same number of entities as there are atoms.

what does entities refer to? (6 things)

atoms, ions, molecules, formular units, electrons, or any type of particle

what is Avogadro’s number?

6.022 × 10²³

define molar mass

a substance’s mass per mole of its entities

how do you calculate the molar mass of a compound? (AM=atomic mass)

AM x (substance) + AM x (substance) = M

what is the molar mass of NaOH?

AM(Na)+AM(H)+AM(O) = 22.99 g/mol+1.008 g/mol+16.00 g/mol = 40.00 g/mol

how do you get mass from # of moles and molar mass?

mass (g) = (# of mol)(# of g/mol)

how do you get the # of moles from mass (g) and molar mass?

no. of moles = (mass (g))/(# g/mol)

how do you get the # of entities?

no. of entities = (# of mol)(N_A)

how do you get the # of moles from entities?

no. mol = (# of entities)/(N_A)

how do you find the mass percent from the chemical formula?

[(atoms of X in formula)(atomic mass of X(amu))/(molecular (or formula) mass of compound (amu))] x 100

what is another way you can find the mass percentage from a chemical formula?

[(moles of X in formula)(molar mass of X (g/mol))/(mass (g) of 1 mol of compound)] x 100

how do you find the mass fraction?

mass of any element in sample = mass of compound x (mass of element in 1 mol of compound/mass of 1 mol of compound)

define empirical formula

the simplest formula for a compound that agrees with the elemental analysis. it is the lower whole number of moles and gives the relative umber of atoms of each element present.

define molecular formula

shows the actual number of atoms of each element in a molecule of the compound

what is the whole-number multiple of the empirical formula?

molar mass (g/mol)/empirical formula mass (g/mol) = whole number multiple

define limiting reagent

limits the amount of product that can form, substance will be completely used up in the reaction

define excess reagent

the reactant that is not limiting, substance will be left over

what is a way you can determine if a substance is a limiting reagent or excess reagent? for aA + bB → cC

if mol A/mol B > a/b then A is excess reagent, B is limiting reagent; if mol A/mol B < a/b then A is limiting reagent, B is excess reagent

define theoretical yield

amount of product calculated using the molar ratios from the balanced equation

define actual yield

amount of product actually obtained; actual yield should be less than or equal to theoretical yield

how do you calculate percent yield?

% yield = (actual yield/theoretical yield) x 100

what is the # of significant figures in 0.2059?

4

convert 350 nanometers to meters

350 nm x 1 m/ 10⁹ nm = 3.5 × 10^-7m

calculate (12.75-13.84)/(7.575-3.154) with the correct significant figures

-.247