unit 6 - periodic table Flashcards
father of periodic table
Mendeleev
why do elements in a group have similar chemical properties
same # of valence electrons
atomic number
number of protons (nuclear charge)
periodic table is arranged according to what
atomic number
as you move down a group, atomic number…
increases
atomic radius
distance between the nucleus and farthest electron
what is the atomic radius group trend
atomic radius increases as you go down the group
why does the atomic radius increase as you go down a group
more occupied principal energy levels, creates a greater distance between the atom’s nucleus and its furthest electron
first ionization energy
the amount of energy needed to remove the most loosely bound electron from the valence shell
(measures how easy/hard an atom loses electrons)
IE trend of a group
decreases as you go down a group
why does IE decrease as you go down a group
atoms with a larger radius have valence electrons that are farther away from their nucleus, so its easier to lose electrons
electronegativity
a measure of the attraction of a nucleus of one atom for another atom’s valence electrons
EN group trend
decreases as you go down the group
why does EN decrease as you go down a group
atoms with a BIG RADIUS, have a LOW EN. attraction for another atom’s electrons decreases with more occupied rings, because its nucleus is further from another atom’s valence shell
metallic property
measure of how easily an element loses electrons
trend of metallic property in groups
the metallic property increases as you go down the group; lose electrons easily
why do metallic properties increase as you move down a group
elements on the bottom of the group have Low I.E. and Low E.N. so they lose electrons very easily/react easily
group 1 is called
alkalai metals
characteristics of alkalai metals
- extremely active
- form strong bases
group 2 is called
alkaline earth metals
characteristics of alkaline earth metals
- very active; but not as much as the alkalai metals
properties of groups 1 & 2
- found only in compounds in nature
- are the most active metals on the periodic table
- lose electrons easily (low IE & EN)
- form only ionic compounds
- from stable compounds (hard to decompose)
- group 1 elements are more active than group 2
group 3 to 12 (transition metals)
- have multiple oxidation states
- can form compounds which have colored ions inwater
- some transition elements are found commonly in the elemental form nature
- Hg (Mercury) only metal - liquid at room temperature
group 13 - boron’s family
boron is metalloid, rest are metal
group 14 - carbon’s family
C - non metal
Si & Ge - metalloid
Sn & Pb - metal
group 15 - nitrogen’s family
N & P - nonmetal
As & Sb - metalloid
Bi - metal
nitrogen is gas, rest solid
group 16 - oxygen’s family
O, S, Se - nonmetal
Te - metalloid
Po - metal
oxygen is gas, rest solid
group 17 - halogens
- ALL halogens have 7 valence electrons (gain 1 electron to become -1 ions)
F - gas
Cl - gas
Br - liquid at room temp
I - solid
At - solid
properties of groups 15, 16, and 17
- high electronegativity (gain another atom’s electrons easily)
- high ionization energy (do not lose their electrons easily)
group 18 - noble gases
- all are non metals and gases at room temp
- DO NOT react with other elements because they have filled/stable outer shell
**8 valence electrons = full shell (except He)
characteristics of a period
elements in the same period:
- number of occupied PEL’s is same
as one move –> across a period, atomic number
increases
as one move –> across a period, number of valence electrons
increases
as one move –> across a period, atomic radius
decreases because energy levels are kept closer to the nucleus, because of a greater nuclear charge
- more protons pull electrons closer to the nucleus and atomic radius decreases
as one move –> across a period, ionization energy
increases, takes more energy to remove electrons from nonmetals (right) than metals (left)
**nonmetals are more attracted to their electrons
why does IE increase as you move across a period
greater nuclear charge; electrons are held closer to the nucleus due to a smaller radius
as one move –> across a period, electronegativity
increases, the attraction for another atom’s electrons increases
***atomic radius decreases; atom’s nucleus is closer to another atom’s valence electrons
why does EN increase as you move across a period
greater nuclear charge, distance between that atom’s nucleus and another atom’s electrons decreases
what percent of all elements are metals
75% of all elements are Metals
where are most active metals found
lower left of the table (Francium)
properties of metals
- have luster (shine); mobile electrons
- ductile: can be drawn into a wire
- malleable: can be hammered into shape
- good conductor of heat and electricity
- all are solids at room temp, except Hg (liquid)
- lose electrons become (+) ions
- low IE and low EN
compare ionic radius and atomic radius of a metal
ionic radius is smaller than atomic radius
what is the most reactive metal
Francium (Fr)
properties of nonmetals
- found on the right of the staircase
- most are gases; some are solids
- Br is the only liquid nonmetal
- I is a solid nonmetal at room temp
- F is the most reactive nonmetal
- lack luster; have a dull surface
- not malleable or ductile, tend to be brittle
- poor conductors of electricity or heat
- nonmetals gain electrons become (-) ions
what’s the most reactive non-metal
F or Fluorine
compare the ionic radius and atomic radius of nonmetals
ionic radius is larger than atomic radius
properties of metalloids (semi-metals)
- elements at the staircase between the metals and nonmetals
- have some properties of both
ex: malleable, bad conductors - 6 metalloids to know: B, Si, As, Te, Ge, Sb
highest EN
Fluorine
highest IE
Helium
