chem

Dalton's Theory (5)

-atoms are indivisible -all atoms of an element are identical -atoms of different elements are different -atoms combine in fixed ratios to form compounds -atoms cannot be created or destroyed

molecular geometry (2 electrons around central atom)

0 lone pairs - linear 1 lone pair - bent 2 lone pairs - bent

molecular geometry (4 electrons around central atom)

0 lone pairs - tetrahedral

molecular geometry (3 electrons around central atom)

0 lone pairs - trigonal planear 1 lone pair - trigonal pyramid

Pressure unit conversions

1 atm = 101.325 kPa = 760 torr = 760 mm Hg

to find empirical formula of a compound from masses

1. divide all masses by molar mass 2. take the quotient of those and divide them by each other=x 3. resulting number is the ratio (1:x)

molar volume

22.4 L/mol

Avagadro's number

6.02 x 10^23

theory (5 things)

A hypothesis that has been tested with a significant amount of data -testable -falsifiable -supported by many observations -can explain observations -can be used to make predictions

pure substance

A sample of matter, either a single element or a single compound, that has definite chemical and physical properties

amorphous solid

A solid made up of particles that are not arranged in a regular pattern -rapid cooling -no long range order -compressible

scientific law (4 things)

A statement that describes what scientists expect to happen every time under a particular set of conditions -testable -falsifiable -supported by many observations -can be used to make predictions

Standard Temperature and Pressure (STP)

A temperature of 273 K and a pressure of 1.00 atm

Hypothesis (3 things)

A testable prediction -testable -falsifiable -can explain observations

isotopes

Atoms of the same element that have different numbers of neutrons

Plasma properties

Conductors of electricity, at extreme temperatures, low density fill space, high kinetic energy, cations

band theory

Electrons move among orbitals of different energies, electrons move freely among atoms (delocalized)

Rutherford

Gold foil experiment, discovered nucleus most of the mass is in the nucleus most of the atom is empty space

Democritus

Greek philosopher that said all matter is made of tiny particles called "atomos" or atoms

Which scientist provided a foundation for John Dalton's work on the atomic structure?

Joseph Proust

Gay-Lussac's Law

P1/T1=P2/T2

Combined Gas Law

P1V1/T1=P2V2/T2 (constant n) (n is moles of gas)

Boyle's Law

P1V1=P2V2

Ideal Gas Law

PV=nRT (R=.08206)

Thompson's Atomic Model

Plum pudding model - positive pudding sprinkled with negative electrons

What is the empirical formula for a compound if a sample contains 1.0 g of S and 1.5 g of O?

SO3

ionization energy

The amount of energy required to remove an electron from an atom in the gas phase

photoelectric effect

The emission of electrons when electromagnetic radiation, such as light, hits a material, developed by Einstein, refuted Rutherford's atomic model

electron domain geometry

The three-dimensional arrangement of the electron domains around an atom sp-linear sp^2-trigonal planear sp^3-tetrahedral

mode

The value that occurs most frequently in a given data set.

Charles' Law

V1/T1=V2/T2

Avogadro's Law

V1/n1=V2/n2

A piece of limestone erodes due to acid rain. This process can be best described as a a. slow chemical change. b. rapid chemical change. c. slow physical change. d. rapid physical change.

a

How was the work of Newlands similar to that of Mendeleev on the periodic table? a. They both arranged the elements in order of increasing atomic mass. b. They both arranged elements that had similar properties into groups. c. They both predicted the positions of undiscovered elements on the table. d. They both placed the relative atomic mass of each element on the table.

a

Which ion was formed by providing the second ionization energy to remove an electron? a. Ca2+ b. N3- c. Fe3+ d. S2-

a

Which step would help a student find the molecular formula of a compound from the empirical formula? a. Multiply the subscripts of the empirical formula by the value of the ratio of the molar mass of the compound to the empirical molar mass of the compound. b. Subtract the value of the ratio of the molar mass of the compound to the empirical molar mass of the compound from the subscripts of the empirical formula. c. Divide the subscripts of the empirical formula by the value of the ratio of the molar mass of the compound to the empirical molar mass of the compound. d. Add the value of the ratio of the molar mass of the compound to the empirical molar mass of the compound to the subscripts of the empirical formula.

a

polyatomic ion

a charged group of covalently bonded atoms that acts as a single unit

polar bond

a covalent bond in which electrons are shared unequally difference in electronegativity is > 0.5 has partial charges

nonpolar covalent bond

a covalent bond in which the electrons are shared equally by the two atoms difference in electronegativity is < 0.4

single bond

a covalent bond in which two atoms share one pair of electrons, demonstrated by a single line

sigma bond

a single covalent bond that is formed when an electron pair is shared by the direct overlap of bonding orbitals

London Dispersion Forces (LDF)

a temporary attractive force that results when the electrons in two adjacent atoms form temporary dipoles

long range order in crystals

arrangement of particles where they are order over many multiples of the average particle diameter

mean

average

Hydrogen reacts with an element to form a compound. Which element would have the most valence electrons available to react with hydrogen? a. oxygen b. chlorine c. neon d. nitrogen

b

What is the correct chronological order of scientists contributing to the modern periodic table? a. Lavoisier, Newlands, Moseley, Dobereiner, and Mendeleev b. Lavoisier, Dobereiner, Newlands, Mendeleev, and Moseley c. Moseley, Mendeleev, Newlands, Dobereiner, and Lavoisier

b

What is the number of valence electrons in cadmium (Cd)? a. 1 b. 2 c. 10 d. 12

b

Which information must be known about a compound to find the molecular formula from the empirical formula? a. density b. formula mass c. percent composition d. mole ratio

b

Which statement describes a step in the formation of an ionic bond? a. An attraction occurs between two ions that have the same charge. b. A metal atom forms a cation, and a nonmetal atom forms an anion. c. A more electronegative atom transfers electrons to a less electronegative atom. d. A metal pulls electrons from another metal and produces a force of attraction.

b

adding and subtracting scientific notation

bases must be the same, the same number of decimal places as the least precise value

dipole-induced dipole forces

between polar and nonpolar molecules polar molecules induce charge redistribution in nonpolar molecule

Lattice energy is an estimate of the...

bond strength

ionic bonds

brittle, high melting/boiling point, conducts electricity when in water/molten or in liquid or gas state, forms by one atom stealing an electron from another atom, weaker than covalent

covalent bonds

brittle, low melting point, gas or liquid at room temp, very strong bonds

What happens to ions during bonding to form an ionic compound? a. Cations accept electrons and anions give away electrons. b. Anions and cations share electrons. c. Cations give away electrons and anions accept those electrons.

c

What is the best reason for a student to remove a dangling bracelet when heating test tubes of acidic solutions in a hot-water bath in a chemistry lab? a. to avoid reactions of the metal with gases in the lab b. to reduce the risk of burns from heat conducted through the metal c. to minimize the chance the bracelet pulling over a test tube, causing a spill d. to prevent misreading the temperature of the bath on a thermometer

c

Which property is better explained by the band theory than by the sea-of-electrons model? a. ductility b. thermal conductivity c. luster d. electrical conductivity

c

Which statement describes a major drawback of the Bohr model that caused scientists to replace it? a. It worked only for helium and larger atoms. b. It did not identify the distance between an electron and the nucleus. c. It contradicted the Heisenberg uncertainty principle. d. It stated that spectral lines of atoms are similar.

c

Immisable liquids

cannot dissolve in each other

properties of hydrogen bonds

causes high melting/boiling points because more energy is needed to separate molecules, high surface tension and viscosity, water: solid is less dense than liquid

Solids properties

conductivity depends on the material, high density, fixed shape, low kinetic energy, neutral, cations, or anions

ionic bonds form...

crystals

An investigation involves determining which metal is better for making pots that will cook food faster. Which is the best hypothesis to use for this investigation? a. Copper is better than iron for making pots. b. Copper is more malleable and heats up faster than iron. c. If copper is a better conductor, it will heat up faster than iron. d. If copper heats up faster than iron, it is better for making pots.

d

Members of which group easily lose an electron to form a +1 cation? a. halogens b. alkaline earth metals c. noble gases d. alkali metals

d

Which of the following metal atoms would have the highest conductivity? a. the atom with the smallest radius and the fewest valence electrons b. the atom with the smallest radius and the most valence electrons c. the atom with the largest radius and the fewest valence electrons d. the atom with the largest radius and the most valence electrons

d

electron affinity trends

decreases down a group, increases across a period

electronegativity trends

decreases down a group, increases across a period

ionization energy trend

decreases down a group, increases across a period

Millikan's Atomic Model

discovered the charge on an electron

electron sea model

electrons move freely among atoms (delocalized), electrons all have approximately the same energy

intramolecular forces v. intermolecular forces

forces within molecules (like covalent bonds) v. forces between molecules, a lot weaker

Deposition

gas to solid

accuracy

how close a measured value is to an accepted value

naming acids

hydro- + base name of nonmetal + -ic + acid

Increase in altitude

increase in pressure cooler=slower=hits walls less=less pressure (or opposite)

atomic radii trends

increases down a group, decreases across a period

ionic radii trends

increases down a group, decreases across a period (deceases for cations and then anions but anions are larger because they gain electrons)

naming bases

ionic: cation metal + hydroxide covalent: naming is based on number attached to N ・ammonia (NH3) ・primary amine ・secondary, tertiary, etc

emmisable liquid

liquids dissolve each other

Kinetic Molecular Theory (KMT)

matter is constantly moving in constant, random motion all collisions are elastic

Electron Cloud Model

model of atom in which the electrons seem to form a cloud as they move around the nucleus, explains the probable location of electrons (not specific)

Bohr Model

model of the atom in which electrons move rapidly around the nucleus in paths called orbits, in order for the electrons to change orbits they must absorb or release energy, doesn't explain that higher orbits have lower energies and electrons exist between orbits.

covalent bonds form...

molecules

expanded octect

more than eight valence electrons can be used in bonding

how to find mass from molecules

number of molecules/6.02 x 10^23=x x*molar mass=mass (g)

emission lines

occur when the electrons of an excited atom, element or molecule move from a lower energy level (higher orbital) to a higher energy level (lower orbital)

median

order the data points and find the middle value of the set

pi bonds

overlap of p-orbitals allows additional sharing

Precision

reproducibility of a measured value

Why are pressure and volume inversely proportional?

smaller volume-> more collisions-> higher pressure

formula unit

smallest repeating unit of an ionic compound

Sublimation

solid to gas

dipole-dipole interactions

strongest van der waal force, between polar molecules positive pole attracts negative pole

electronegativity

the ability of an atom to attract electrons from another atom in a compound

electron affinity

the energy associated with the addition of an electron to a gaseous atom

hydrogen bonding

the intermolecular force in which there is an attraction between H bonded to an electronegative atom (usually O, N, or F) and a electronegative atom of another molecule

vapor pressure

the pressure exerted by a gas over a liquid, higher vapor pressure, the easier it is to have the liquid boil

van der Waals forces

the two weakest intermolecular attractions- dispersion interactions and dipole forces

Properties of London Dispersion forces

usually nonpolar molecules but sometimes polar heavier molecule=stronger force usually gases weakest van der waal force

octet rule

when valence shells are filled they are more stable (so have 8 electrons, also not always true) exception example: H only needs 2 to be stable