Properties of periodic groups and elements

By the late 1800s, scientists recognized that certain _______ looked alike and ___________ in similar ways

elements, behaved

Dmitri Mendeleev (1834-1907)

arranged the 60 elements known at that time into groups with similar properties and placed them in order of increasing atomic masses

group

Vertical column in the periodic table

group number

A group number is written at the top of each vertical column (group) in the periodic table

representative elements

an element in an "A" group; as a group these elements display a wide range of physical and chemical properties. In their atoms, the s and p sublevels in the highest occupied energy level are partially filled

transition elements

an element in the center of the periodic table that is designated with the letter B o the group number 3-12

period

A horizontal row of elements in the periodic table

period are counted from

1-7

several groups in the periodic table have _______ _____

special names

group 1A (1) are...

alkali metals

alkali metals

soft, shiny metals

good conductors of heat and electricity

relatively low melting points

react vigorously with water

form white products when combined with oxygen

_________ is not included in the alkali metals

hydrogen

group 2A (2)

alkaline earth metals

alkaline earth metals

shiny metals

not as reactive as alkali metals

group 7A (17)

Halogens

halogens

highly reactive

form compounds with most of the elements

Group 8A (18)

noble gases

noble gases

unreactive

seldom found in combination with other elements

Another feature of the periodic table is the heavy ________ ___ that separates the elements into the metals and the nonmetals

zig zag line

Except for ______, the metals are to the ___ of the line with the nonmetals to the _______.

hydrogen, left, right

metals

shiny solids

ductile (shaped into wires)

malleable (hammered into a flat sheet)

good conductors of heat and electricity

higher melting point than nonmetals

solids at room temperature, except mercury (Hg), which is liquid

nonmetals

not especially shiny, ductile, or malleable

poor conductors of heat and electricity

typically have low melting points and low densities

the elements located along the heavy line are _______

metalloids

Metalloids

have properties of both metals and nonmetals in some respect