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isotopes

atom of same element with different number of neutrons

metalloids

brittle, not great heat conductors and solid at room temp

alkali metals

the most reactive, shiny and mallable

alkaline earth metals

shiny silver white, less reactive

halogens

most reactive group of non metals and forms acid by reacting with hydrogen

noble gases

least reactive with a full outermost orbital

atomic mass

weighted average mass of all isotopes

mass number formula

round atomic mass and subtract the atomic number

dalton

an atom is a solid ball

thomson

a positive ball with electrons

Rutherfords

atom is mostly empty with a nucleus

bohr

electrons orbit nucleus

electronegativity definition

an atoms tendency to attract electrons towards itself

ionization energy definition

the amount of energy needed to remove an electron

atomic radius definition

a measure of the size of chemical elements atom

ionic radius definition

the measure of an atoms ion size within a crystal lattice

shielding definition

phenomenon where inner core electrons block the positive change of nucleus from fully reaching outer valence electrons

electronegativity trend across

increase

ionization energy trend across

increase

atomic radius trend across

decrease

ionic radius trend across

decrease

shielding trend across

constant

shielding trend down

increase

ion

a charged atom