Unit 3: Periodicity Flashcards
Properties of Metal
- usually a solid @ room temp (except Hg)
- shiny/lustrous
- malleable: can be hammered into sheets
- good conductors of heat + electricity
- high m.p.
- ductile: can be drawn into wires
- lose e-
- low values for electronegativity, ionization energy, and electron affinity values
Properties of Nonmetals
- dull/lack luster
- poor conductor
-insulator of heat + electricity - gain e-
- high values for electronegativity, ionization energy, and electron affinity values
Properties of Metalloids
- Have characteristics of both metals & nonmetals
- Physical properties/ appearance resemble metals
- Chemical properties resemble nonmetals
Periods
Horizontal Rows (1-7)
Groups
Vertical columns (1-18)
- sometime groups 3-12 are “omitted” and we call the remaining groups, Groups 1A-8A
Group 1
Alkali metals
Groups 3-12
Transition metals (d-block)
Group 17
Halogens
Group 18
Noble gasses
Elements 58-71
Lanthanoids (f-block)
Elements 90-103
Actinoids (f-block)
Atomic Radius (group-trend)
As you move down a group, atomic radius increases
(“snowman effect”
Why does atomic radius increase as you move down a group?
As the # of occupied energy levels increases, so does the size of the atom
Atomic Radius (period-trend)
As you move across a period, atomic radius decreases
Why does the atomic radius decrease as you move across a period?
Same: e- are being added to the same energy level
Different: the # of protons increases so the attraction between the increasingly positive center and (-) e- increases. This attraction “pulls in” the outer e-
Ionic Radius (Cations) (Group)
Cations increase in size down a group as the outer energy level gets further from the nucleus (less attraction)
Ionic Radius (Cations) (Period)
Cations in a period contain the same # of e- but an increasing # of protons, creasing the attraction between the (+) center and the (-) e-. thus decreasing the radius
Ionic Radius (Anions) (Group)
Anions increase in size down a group as the outer energy level gets further from the nucleus (less attraction)