electrons in atoms - chem test

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scientific notation

ways of expressing very large or very small numbers

when the decimal is moved to the left in scientific notation

the exponent is positive

when the decimal is moved to the right in scientific notation

the exponent is negative

standard notation

the opposite of scientific notation

light

a kind of electromagnetic radiation

electromagnetic radiation

a form of energy that travels space as a wave moving at the speed of light

for example ROYGBIV

*all electromagnetic radiation travels at the same speed of light when measured in a vacuum*

*all electromagnetic radiation travels at the same speed of light when measured in a vacuum*

speed of light

(3.0 × 10⁸ m/s)

DOES NOT count in sig figs

wavelength

measures a wave from crest to crest or trough to trough in meters

frequency

measures how the speed of a wave in hertz (hz or sec^-1 )

principle quantum number

the maximum number of electrons that can fit in an energy level

2n²

n = energy level

electron configurations

the way electrons are arranged in various orbitals around the nuclei of atoms

aufbau principle

electrons enter the lowest energy first

pauli exclusion principle

at most 2 electrons per orbital

to show the different direction of spin a pair in the same orbital is written with arrows

hund’s rule

when electrons occupy orbitals of equal energy, they dont pair up until they have to

the exceptions of electron configurations

elements that are chromium, copper, or in their same group

the periodic table law

when elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties

periods

horizontal rows of the periodic table

groups (or families)

the vertical rows of a periodic table

metals

electrical conductors, have luster, ductile and malleable

nonmetals

generally brittle and non-lustrous, poor conductors of heat and electricity

metalloids

border the line on the periodic table and its properties are intermediate between metal and nonmetals

alkali metals

group 1 of periodic table that forms a “base” when reacting with water

alkali earth metals

group 2 of periodic table that forms bases with water, do not dissolve well, hence “earth metals”

halogens

group 17 of periodic table and means “salt forming”

noble gases

group 18 of periodic table that rarely take part in a reaction, very stable