Chemistry Midterm Review

exothermic

releases energy

endothermic

absorbs energy

significant digits

meaningful digits in a measured quantity

mass

the amount of matter in an object

matter

Anything that has mass and takes up space

liquid

no definite shape but has a definite volume.

solid

Definite shape and volume

gas

no definite shape or volume

density

mass/volume

displacement

final position - initial position

intensive property

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

solution

A homogeneous mixture of two or more substances

compound

A substance made up of atoms of two or more different elements joined by chemical bonds

element

A pure substance made of only one kind of atom

Crystallization

a separation technique that produces pure solid particles of a substance from a solution that contains the dissolved substance

distillation

A process that separates the substances in a solution based on their boiling points

filtration

A process that separates materials based on the size of their particles.

chromatography

the separation of a mixture by passing it in solution or suspension or as a vapor through a medium in which the components move at different rates.

chemical change

A change that occurs when one or more substances change into entirely new substances with different properties.

physical change

A change in a substance that does not change its identity

law of conservation of matter

matter cannot be created or destroyed

constant composition

when every particle in a substance is exactly the same

law of conservation of energy

Energy cannot be created or destroyed

multiple proportions

Two elements combine with each other to form more than one compound

% mass formula

(mass element/total mass of compound)100

isotopes

Atoms with the same number of protons but different numbers of neutrons

neutral atom

same number of protons and electrons

which particle was the last particle discovered and why

neutron because it has no charge and is located inside the nucleus

percent abundance equation

Average Mass \= (%)•(Mass of Isotope A) + (%)•(Mass of Isotope B) +...

isotope names

element - atomic mass \#

how do nonmetals and metal react with each other

metals will always lose electrons to nonmetals because metals have low ionization energy and low numbers of valence electrons

cation

positive ion

anion

negative ion

ionic bond

the attraction between oppositely charged ions - trade electrons

covalent bond

A chemical bond formed when two atoms share electrons

nuclear fusion

The process by which two or more small nuclei fuse to make a bigger nucleus

nuclear fission

nuclei of isotopes split apart when struck by neutrons

half-life

length of time required for half of the radioactive atoms in a sample to decay

atom chemical symbol

\# protons+neutrons (on top) \# protons (on bottom) Element symbol (on the side)

electronegativity

a measure of the tendency of an atom to attract a bonding pair of electrons

atomic radius

size of an atom

ionization energy

the energy required to remove an electron from an atom

halogens

Group 7A - toxic, form acids with hydrogen, highly reactive

alkali metals

Group 1, 1 electron in outer level, very reactive, soft, silver, shiny, low density

alkaline earth metals

group 2 - low ionization levels, highly reactive, good electricity conductors

amu

atomic mass unit

frequency

the number of complete wavelengths that pass a point in a given time - red (low) -\> violet (high)

wavelength

The distance between two corresponding parts of a wave - red (long) -\> violet (short)

visible light spectrum

the portion of the electromagnetic spectrum that is visible to the human eye - red (lowest energy) -\> violet (highest energy)

Orbitals/Shells

energy levels that surround the nucleus of an atom

what is the reason for the ionization energy trend?

as atomic number increases in a period, the effective nuclear charge increases

Coulomb's Law

F\=K q₁*q₂/r², magnitude of force between two charges

isoelectronic

having the same number of electrons