chemistry- periodic trends

mendeleev

organized the elements by increasing atomic mass and so that elements in the same row have similar properties

moseley

how the modern one is arranged

mo-seley mo-dern

rearranged the elements by increasing atomic number

periodic law

when elements are arranged in order of increasing atomic number, there is a periodic pattern in their physical/chemical properitea

period

out

horizontal rows

groups

up

vertical

elements in the same group

similar properties

elements in the same period

dont have similar properties

metals

left of staircase

shiny lustorous

malleable

electricity

nonmetals

right of staircase

dull non lustrous

brittle

poor electricity

metalloids

touch the staircase and have properties of both metals and nonmetals

how the radius of atom is found

measuring the distance between the nuclei of two touching atoms and then halving the distance

atomic radius

½ of the distance between the nuclei of two like atoms

radius of atom is dependent on

nuclear charge

distance between electrons and nucleus

period trend of atomic size (across)

atomic size decreases from left to right

have the same number of occupied energy levels but a greater number of protons

group trend of atomic size (down)

atomic size will increase as you move down a group

moving down a group there is a greater number of occupied enehry levels

shielding effect

the inner electrons shield or block the attraction from the nucleus

while there is an increase in number of protons down a group moving(nuclear charge) this does not effect the magnitude of attraction from the nucleus due to this affect

as you move top to bottom down a group on the periodic table the size of an atom will ___. This happens because as you move down the group each elements has one more occupied __ lthan the last one.

increase; energy level

as you move left to right across a period on the periodic table the size of an atom will . This happens because as yiu move across a prriod each elements has one more __ in its nucleus than the last one.

decrease; proton

the __ effect is caused by inner electrons interfering with the attraction os outer electrons for the protons in the nucleus

shielding

group 1

alkali metals

d block

transition metals

the size of an atom is due mainly to the number of occupied

energy levels

as you move across a period from left to right, the size of an atom will __. This is due to the increased number of ___.

decrease; protons

as you move down a group, the size of the atoms will __, due to a greater number of __as you move down.

increase; energy levels

the amount of energy required to remove the most loosely held electron from an atom is called the 

ionization energy

ionization energy will increase as you move ____ and decrease as you move __

left to right; down

upside down snow man

the size of a positive ion is always _ than the size of the neutral atom from which it was made

smaller

Cl > Cl +2

the size of a negative ion is always __ than the size of the neutral atom from which it was made

larger

Cl < Cl-2

the ability of an atom to attract electrons to itself when the atom is in a chemical bond

electronegativity

upside down snowman