chapter 2 chem: atoms and elements

alkali metals

group 1

alkaline earth metals

group 2

phietogens

group 15

chalcogens

group 16

halogens

group 17

noble gasses

group 18

lanthanides

first row of excluded 

actimides

second row of excluded

mendeleev

organized elements by recurring/periodic chem properties

diatomic elements

H, N, F, O, I, Cl, B 

homonuclear

compounds composed of identical elements

heteronuclear

compounds composed of different elements

molar mass

grams divided by mole

atom

a single element with no charge

ion

a single element with a positive or negative charge

molecule

a compound with 2 or more nonmetals together

formula unit

general term for a compound composed of a metal and nonmetal

Avogadro’s number

6.022×10²³

converting between mass and particles

atoms/ions/molecules/formula units to mole to grams

nucleus

neutrons and protons

1 AMU is how many kg?

1.66×10^-27 kg

mass number =

protons + neutrons

atomic number =

protons

neutrons =

mass number (protons + neutrons) - atomic number (protons)

protons =

mass number (protons + neutrons) OR protons = electrons

electrons =

protons

isoelectronic

elements that have the same number of electrons

atomic mass formula

[(isotope mass 1)(fractional abundance)] + [(isotope mass 2)(fractional abundance)]

mass ratio

element with larger mass on top