Chapter 19 - murraysphysical
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Transcript Chapter 19 - murraysphysical
Chapter 19
Elements and Their Properties
Metals
Properties of Metals
– Conduct heat and electricity.
– Luster- reflect light well.
– Malleable- can be hammered or rolled
into sheets.
– Ductile- can be drawn into wires.
Metals- Cont.
– Ionic Bonds- combine
with nonmetals by
losing electrons.
Metals- Cont.
– Metallic Bonds- 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
nonmetals.
Alkali Metals
The Alkali Metals- softer and
more reactive than other
metals.
– Highly reactive with oxygen and
water; don’t occur naturally in
elemental forms.
– Combine readily with other
elements due to single
electrons in the outer energy
level.
Alkali Metals are
found in Group 1 of
the Periodic Table.
Alkali Metals- Cont.
- Multiple uses
– Human Health- Na, K, Li
– Photocells- some depend on Ru or Cs
– Francium- a radioactive element which breaks
down giving off particles and energy
Alkaline Earth Metals
Alkaline Earth Metals- not found naturally
in elemental form; two electrons in outer
energy level.
Alkaline Earth Metals
are found in Group 2
of the Periodic Table.
Alkaline Earth Metals
– 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
formerly used in cancer
treatment
Transition Metals
Transition Metals- they often occur in
nature as uncombined elements
Transition Metals are
found in Groups 3-12
of the Periodic Table.
Transition Metals- Cont.
– Typically form colored
compoundsChromium found in
rubies and emeralds
Chromium in it’s raw form.
Transition Metals- Cont.
– Iron Triad- Iron, Cobalt, and Nickel
Iron- Most widely used of all metals and main
ingredient in steel; abundant in Earth’s crust
Cobalt & Nickel- used in some steels
Nickel used to coat other metals
Transition Metals- Cont.
– Copper, silver, 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 and fillings
Transition Metals- Cont.
– Zinc, Cadmium, Mercury- Group 12 on the
periodic table
Zinc & Cadmium- often used to coat or plate other
metals
Mercury- only room temperature liquid metal; used
in thermometers and batteries
Transition Metals- Cont.
– Inner transition- seem disconnected from the
rest of the periodic table
Lanthanides- include La, Cr, Pr, Sm, Eu, Gd, Tb
Actinides- all are radioactive and unstable;
Uranium is the best known
Uranium in raw form.
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
Non Metals- Cont.
– Ionic compounds form when nonmetals gain
electrons from metals and become negative
ions.
– Covalent compounds form when nonmetals
share electrons with other nonmetals.
Nonmetals- Cont.
Hydrogen- most common
element in universe
– Diatomic molecule- two
atoms of the same element
in a covalent compound
– Highly reactive element
found mostly on Earth as
part of a water compound
Nonmetals- Cont.
Halogens- include Bromine, Iodine,
Fluorine, Chlorine, and Astatine
Halogens are found in
group 17 of the
periodic table.
Nonmetals- Cont.
– A salt forms when a halogen gains one
electron from a metal
– Uses of Halogens
Chlorine- disinfectant and bleach
Bromine- dyes in cosmetics
Iodine- hormone regulation
– Sublimation- a solid changes directly into a
gas without first becoming a liquid
Nonmetals- Cont.
Noble Gases- exist as isolated, stable
atoms
– Helium- used in blimps and balloons
– Neon, Argon, Krypton- used in lights
Review Question
C12 H22 O11
Number of atoms
C=
H=
O=
Total number of atoms:________
Mixed Groups
Properties of Metalloids
Form ionic and covalent bonds
Have some metallic and some nonmetallic
properties
Partial conduction gives them semiconductor
characteristics
Mixed Groups- Cont.
Boron Group- named for the first element
in Group 13
– Boron- use in water softening products,
antiseptic, and fuels
– Aluminum- abundant in Earth’s crust; used in
cans, foil wrap, pans, building materials, and
aircraft
Mixed Groups- Cont.
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- found in sand, rocks, and soil
The main component in semiconductors, which conduct
electricity under certain conditions
–
–
–
–
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.
Mixed Groups- Cont.
Nitrogen Group- five electrons in outer
energy level; trend to form covalent bonds
– Nitrogen- used to make nitrates and ammonia
– Phosphorus- used in water softeners,
fertilizers, match heads, fine china
– Antimony and Bismuth- used with other
metals to lower melting points
Mixed Groups- Cont.
Oxygen or 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
– Te & Po are also oxygen group elements.
Mixed Groups- Cont.
Synthetic elements- scientists create elements
not usually found on Earth; synthetic elements
usually disintegrate quickly
– Uranium can be made into Neptunium which forms
plutonium when it disintegrates
– Plutonium can be changed into Americum, which is
used in smoke detectors.
– Transuranium have more than 92 protons and are
synthetic and unstable
The study of synthetic elements helps scientists to
understand the forces holding the nucleus together.
Element 114 lasted for 30 seconds.
It combined 114 protons with 175 neutrons.
It broke apart due to enormous repulsion between the
protons.