chem final

Matter

anything that has mass and occupies space

Chemistry

the study of the composition of matter and the changes matter undergoes

Extensive property

a property that depends on the amount of matter in a sample

Intensive property

a property that depends on the type of matter and not the amount

Substance

matter with a uniform and definite composition with identical intensive properties

Element

a pure substance made of one kind of atom and the simplest form of matter

Compound

a substance made of two or more elements chemically combined in a fixed ratio

Chemical symbol

shorthand representation of an element

Chemical formula

representation of a compound using symbols and subscripts

Physical property

a characteristic observed or measured without changing composition

Physical change

change in physical properties or state without changing composition and caused by energy or force

Chemical change

change that produces substances with different compositions through a chemical reaction

Solid

state of matter with definite shape and definite volume

Liquid

state of matter with definite volume but indefinite shape and ability to flow

Gas

state of matter with indefinite shape and volume and refers to substances that exist in the gaseous state at room temperature

Vapor

gaseous form of a substance normally liquid or solid at room temperature

Reversible physical change

physical change involving a change of state that can be undone

Irreversible physical change

physical change that cannot be easily undone

Chemical property

ability of a substance to undergo a chemical change

Reactant

substance present at the start of a chemical reaction

Product

substance formed at the end of a chemical reaction

Indicators of chemical change

gas production energy transfer precipitate formation or color change

Law of conservation of mass

mass is conserved in all physical and chemical changes

Mixture

physical blend of two or more substances that retain their individual properties

Heterogeneous mixture

mixture with nonuniform composition and multiple phases

Homogeneous mixture

mixture with uniform composition and a single phase

Phase

any part of a sample with uniform composition and properties

Filtration

separation method used to separate a solid from a liquid

Distillation

separation method based on differences in boiling points to separate liquids or dissolved solids

Measurement

a quantity that includes both a numerical value and a unit

Scientific notation

a number written as a coefficient multiplied by ten raised to a power

Accuracy

how close a measured value is to the accepted or true value

Precision

how close repeated measurements are to one another

Accepted value

correct value based on reliable references

Experimental value

value obtained through measurement or experiment

Error

difference between experimental value and accepted value

Percent error

error divided by accepted value multiplied by one hundred

Significant figures

all known digits in a measurement plus one estimated digit

Significant figure rules summary

nonzero digits and interior zeros are significant while leading zeros are not and trailing zeros depend on decimal placement

Rounding rules

round based on the digit following the last significant figure

SI system

international system of units used in science based on powers of ten

Meter

SI base unit of length

Liter

commonly used unit of volume equal to one thousand cubic centimeters

Kilogram

SI base unit of mass

Mass

measure of the amount of matter in an object

Weight

force exerted on a mass by gravity

Celsius scale

temperature scale based on water freezing and boiling points

Kelvin scale

absolute temperature scale with zero at absolute zero and no negative values

Temperature conversions

K equals C plus 273 and C equals K minus 273

Energy

capacity to do work or produce heat

Joule

SI unit of energy

Calorie

amount of energy needed to raise one gram of water by one degree Celsius

Conversion factor

ratio of equivalent measurements used to change units

Dimensional analysis

problem solving method using units and conversion factors

Dimensional analysis example

convert 750 dg to grams using 1 g per 10 dg to get 75 g

Dimensional analysis multi step example

convert 2.5 km to cm by km to m to cm resulting in 2.5 x 10^5 cm

Density

mass divided by volume and an intensive property

Density equation

density equals mass divided by volume

Density application

less dense substances float on more dense substances

Atom

smallest particle of an element that retains its identity

Dalton atomic model

atoms are solid indivisible spheres

Dalton atomic theory

all matter is made of atoms atoms of the same element are identical atoms combine in whole number ratios and chemical reactions rearrange atoms without creating or destroying them

Subatomic particles

electrons protons and neutrons

Electron

negatively charged subatomic particle

Proton

positively charged subatomic particle located in the nucleus

Neutron

neutral subatomic particle located in the nucleus

Thomson atomic model

plum pudding model with electrons embedded in a positively charged sphere and first to include electrons

Rutherford atomic model

atom contains a small dense positively charged nucleus and is mostly empty space with electrons surrounding the nucleus

Bohr atomic model

electrons move in fixed quantized energy levels and jump levels by absorbing or releasing energy and works best for hydrogen

Schrödinger quantum mechanical model

electrons exist in orbitals as probability clouds described by mathematics and is the most accurate modern model

Atomic model progression

models evolved from solid atoms to nucleus to energy levels to probability clouds

Atomic number

number of protons in the nucleus of an atom

Mass number

total number of protons and neutrons in an atom

Neutron calculation

neutrons equal mass number minus atomic number

Isotopes

atoms of the same element with different numbers of neutrons

Atomic mass unit

one twelfth the mass of a carbon twelve atom

Atomic mass

weighted average of naturally occurring isotopes

Average atomic mass example

carbon atomic mass equals 12.000 u times 0.9899 plus 13.003 u times 0.0111

Periodic table

arrangement of elements by increasing atomic number showing periodic trends

Period

horizontal row on the periodic table representing an energy level

Group

vertical column on the periodic table with similar chemical properties

Group rule

elements in the same group have similar chemical properties but not always the same physical properties

Metals

shiny malleable ductile good conductors usually solid at room temperature

Nonmetals

dull brittle poor conductors often gases or low density solids

Metalloids

elements with mixed metal and nonmetal properties located along the staircase line

Periodic table dividing line

zigzag staircase separates metals from nonmetals

Atomic radius

measure of atomic size defined as half the distance between nuclei

Atomic size trend

atomic radius increases down a group and decreases across a period

Largest atom

francium is the largest atom

Smallest atom

helium is the smallest atom

Ionization energy

energy required to remove an electron from a gaseous atom

Ionization energy trend

increases across a period and decreases down a group

Highest ionization energy

fluorine has the highest ionization energy excluding noble gases

Hydrogen ionization exception

hydrogen has no second ionization energy because it has only one electron

Electronegativity

ability of an atom to attract electrons in a chemical bond

Electronegativity trend

increases across a period and up a group

Speed of light equation

c equals frequency times wavelength

Speed of light variables

c is speed of light f is frequency and lambda is wavelength

Speed of light example

wavelength equals 3.0 x 10^8 m per second divided by 6.0 x 10^14 Hz giving 5.0 x 10^-7 m

Photon energy equation

E equals Planck constant times frequency