Download ELEMENTS and THEIR PROPERTIES

ELEMENTS and
THEIR
PROPERTIES
Chapter 19
THE PERIODIC TABLE( pages 518-519 in text)
The Periodic Table
• In the late 1800’s Dmitri Mendeleev, a Russian chemist, discovered a
way of organizing the elements. This became known as the first
periodic table.
• He put the elements in order by their atomic mass, today we have
them in order of their atomic number.
• He left blank spaces in his table to keep the elements lined properly.
He new from this that there were elements not yet discovered.
Properties of metals
1.
2.
3.
4.
5.
conduct heat and electricity
Luster- reflect light well
Malleable- can be hammered or rolled into sheets
Ductile- can be drawn into wires
Ionic bonding- combine with non-metals by losing
electrons
6. Metallic bonding- positively charged metallic ions are
surrounded by a cloud of electrons; ions are in sliding
layers and electrons are weakly held; readily form ionic
bonds with non-metals.
The Alkali Metals- softer and more reactive
then other metals
• Highly reactive with oxygen and water; don’t occur naturally as
elements forms.
• Combine readily with other elements due to single electron in outer
energy levels
• Multiple uses:
Human health- sodium, potassium, and lithium compounds
Photocells- some depend on rubidium or cesium
Francium- a radioactive element which breaks down giving off
particles and energy.
The Alkaline Earth Metals- not found
naturally in element form; two electrons in outer
energy level
• Applications- strontium and magnesium found in fireworks;
magnesium in vehicles, ladders, and bats; calcium in statues and
countertops
• Human Body- calcium in bones; barium in disease diagnoses; radium
formelrly used in cancer treatment
Transition Elements- they often occur
in nature as uncombined elements
• Typically form colored compounds- chromium found in rubies and
emeralds
• Iron triad- iron, cobalt, and nickel
iron- most widely used of all metals and main ingredient in steel;
abundant in Earth’s crust
Cobalt and Nickel- used in some steels
Nickel- used to coat other metals
Copper, silver, and gold- coinage metals
since once were commonly used in coins
• Copper- used in electric wiring because it is a superior electricity
conductor
• Silver- used in photographic film and paper; jewelry
• Gold- used in jewelry
Zinc, cadmium, mercury- group 12 on the
periodic table
• Zinc and cadmium- often used to coat or plate other metals.
• Mercury- only room temperature metal; used in thermometers and
batteries
The inner Transition metals- seem
disconnected from the rest of the periodic table
• The Lathanides- include lanthanum, cerium, praseodymium,
amarium, europium, gadolinium, and terbium.
• The Actinides- all are radioactive and unstable; uranium is the best
known.
NONMETALS
PROPERTIES OF NONMETALS- usually gases or brittle
solids at room temperature; are not malleable or ductile; usually poor
conductors of heat and electricity; usually not lustrous
Ionic compounds- form when nonmetals gain electrons from metals
and become negative ions
Covalent compounds- form when nonmetals share electrons with other
nonmetals.
Hydrogen- most common element in
the universe.
• A diatomic molecule- two atoms of the same element in a covalent
bond
• Highly reactive element found in mostly on Earth as part of a water
compound.
The Halogens- include Bromine, iodine,
fluorine, chlorine, and astatine
• A salt forms when a halogen gains one electron from a metal
• Use of halogens:
chlorine- disinfectant and bleach
Bromine- dyes in cosmetics
Iodine- hormone regulation
Sublimation- a solid changes directly into a gas without it first
becoming a liquid
The noble gases- exist as isolated, stable
atoms
• Helium- used in blimps and balloons
• Neon, argon, and krypton- used in lights
Properties of metalloids- form ionic and
covalent bonds; have some metallic and some
non-metallic properties; partial conduction gives
them semiconductor characteristics.
The Boron group- named for the first
element in group 13
• Boron- used in water softening products; antiseptics and fuels
• Aluminium- abundant in Earth’s crust; used in cans, foil wrap, pans,
building materials’ and aircraft
The Carbon Group- four electrons in
outer energy level
• Carbon- found in coal, oil, natural gas and foods
• Silicon occurs as an allotrope- same element with different molecular
structures
silicon is found in sand, rocks, and soil
The main component in semiconductors, which conduct electricity under
certain conditions
Continued…
• Germanium- also used in semiconductors
• Tin- used to coat other metals
• Lead- toxic, so no longer used in paint
• Diamonds, graphite, and buckminsterfullerene are all allotropes of
carbon
The Nitrogen group- five electrons in outer
energy level; tend to form covalent bonds
• Nitrogen- used to make nitrates and ammonia
• Phosphorus- used in water softners, fertilizers, match heads, and fine
china
• Antimony and bismuth used with other metals to lower their melting
points
The Oxygen group of group 16
• Oxygen- makes up 20% of air, is used by living things in respiration,
and provides protection from the Sun’s radiation.
• Sulfur- used to form sulfides for pigment in paint.
• Selenium- used in photocopiers and multivitamins
• Tellurium and polonium are also oxygen group elements.
Synthetic elements- scientists create
elements not usually found on Earth; synthetic
elements usually disintegrate quickly.