unit 3 Flashcards
what group are alkaili metals
group 1
what group are alkali earth metals
group 2
what group are halogens
group 17
what group are noble gases
group 18
who made the first periodic table
Dimitri Mendeleev
how did Dimitri Mendeleev organize the periodic table
by atomic mass
who revised the periodic table
Henry Moseley
how did Henry Moseley organize the Periodic table
by atomic number
what are horizontal rows of the periodic table called
periods
what are vertical columns of the periodic table called
groups or families
what are valence electrons
outermost electrons occupying the highest energy level
what is shielding
inner layer electrons occupying lower energy levels
what are the trends of shielding
shielding increases from top to bottom, and is constant left to right
why does shielding increase from top to bottom
as move down a group another energy level is added
why is shielding constant from left to right
because as you move across the periodic table only valence electrons are being added
what is atomic radius
the measure of distance between two nuclei of two identical atoms of an element
what are the trends of atomic radius
increases from top to bottom, and decreases from left to right
why does atomic radius increases from top to bottom
because there are more levels of electrons
why does atomic radius decrease from left to right
because more positive nucleus pulls electron clouds tighter
what is ionization energy
the energy required to remove an electron from an atom
what are the trends of ionization energy
decreases from top to bottom, increases from left to right
what does ionization energy decrease from top to bottom
because it is easier to remove an electron from an atom that is shielded and and distance from the nucleus
why does ionization energy increase from left to right
because it is harder to take electrons from tightly held electron clouds
what is electronegativity
the ability of an atom to attract electrons
