Gen Chem 1: Chapters 1-2

matter

anything that occupies space and has mass (solid, liquid, gas)

classifications of matter

mixture

a combination of two or more substances in which the substances retain their distinct identities (homogenous/heterogenous)

homogenous mixture

the composition of the mixture is the same throughout ("no chunks")

heterogenous mixture

the composition is not uniform ("has chunks")

substances

a form of matter that has a definite (constant) composition and distinct properties (elements/compounds)

element

a substance that cannot be separated further into simpler substances

compound

a substance composed of atoms of two or more elements chemically united in fixed proportions

molecule

consists of two or more atoms joined together by chemical bonds (moves as one "unit")

atom

smallest particle of an element

physical property

can be observed without changing the composition of a substance (color, volume, mass, melting/freezing pt, length, opacity, pressure, boiling/condensation pt)

physical change

the form of matter changes, but NOT molecular composition (melting, freezing, vaporization, condensation, sublimation, deposition)

sublimation

solid to gas

deposition

gas to solid

chemical property

a property that is evident during a chemical reaction (toxicity, reactivity, heat of combustion, chemical stability, oxidation state, enthalpy of formation, chemical bonds, flammability)

chemical change

the molecular composition changes; a reaction

extensive property

depends on how much matter is being considered; can be added together (volume, mass, size, weight, length, heat)

intensive property

does NOT depend on how much matter is being considered; NOT additive (boiling point, color, temperature, luster, hardness)

how many m in 1 Gm (gigameter)

1 x 10^9 m

how many m in 1 Mm (megameter)

1 x 10^6 m

how many μm (micrometers) in 1 m

1 x 10^6 μm

how many nm (nanometers) in 1 m

1 x 10^9 nm

how many pm (picometers) in 1 m

1 x 10^12 pm

how many fm (femtometers) in 1 m

1 x 10^15 fm

volume

length x width x height (measured quantity with derived units: 1 mL = 1 cm^3) -- NOTE: when units are squared/cubed, the conversion factors themselves must also be squared/cubed

density

mass/volume

(solid and liquid units: g/mL; gas units: g/L)

when do leading zeroes count as sig figs?

never (ex: 0.0007 = 1 sig fig)

when do interior zeroes count as sig figs?

always (ex: 2075 = 4 sig figs)

when do trailing zeroes count as sig figs?

only when there is a decimal place (ex: 1450 = 3 sig figs, but 1450. = 4 sig figs)

how to determine amount of sig figs when multiplying/dividing

answer should have the same number of sig figs as the input with the SMALLEST number of sig figs (ex: 1.180 x 0.0078 should have 2 sig figs)

how to determine amount of sig figs when adding/subtracting

answer should be rounded to the same decimal place as the LEAST PRECISE input (fewest decimal places) (ex: 89.334 + 1.1 should be rounded to the tenths place (0.1))

Z

atomic number - # of protons in an element (defines the element)

A

mass number - # of protons + # of neutrons

ions

an atom that is electrically charged

anion

a negatively charged atom (more electrons than protons)

cation

a positively charged atom (less electrons than protons)

isotope

atoms of the same element with different number of neutrons

atomic mass

average mass of all naturally occurring isotopes of an element (measured in amu; found on periodic table)

molecular formula

shows the exact number of atoms of each element in one molecule

empirical formula

shows which elements are present and the simplest whole-number ratio of their elements

isomers

compounds with the same chemical formula but different molecular structures

structural isomers

compounds that differ in how the atoms are connected to each other

spatial isomers

compounds in which the relative orientations of the atoms in space can be different

mole (mol)

an amount in which there are 6.022 x 10^23 "things", such as atoms or molecules

molar mass

the mass (in grams) of 1 mole of atom/molecule of a substance

how to find molar mass of a compound

find the molar mass of each element in the compound, multiply each molar mass by the amount of each element in the compound, then add the products together

ball-and-stick model

space filling model

Dalton's Postulates / The Atomic Theory

1. matter is composed of small particles called atoms. an atom is the smallest unit of an element.

2. all atoms of a given element are identical, having the same size, mass and chemical properties (INCORRECT)

3. the atoms of one element are different from the atoms of all other elements

4. compounds are composed of atoms of more than one element in a whole number ratio. for any given compound, the atoms present are always in the same ratio.

5. a chemical reaction involves only the separation, combination, or rearrangement or atoms; it does not result in the creation or destruction of atoms.