Transcript Ch 19 Elements - cloudfront.net

Ch 19 Elements
Metals, Nonmetals, Metalloids
Alkali and Alkali Earth Metals
Ionic Bonding, Metallic Bonding, Covalent Bonding
Bellwork:
List 8 ways that elements are important in your life.
(Write on your packet.)
What are we going to learn today…
• 3202.1.14 Use the periodic table to identify the characteristics
and properties of metals, nonmetals, metalloids
Metals
• Describe the properties of a typical metal
• Identify the alkali metals and alkali earth metals
• Differentiate among three groups of transition elements
Metals
• Good conductors of heat and
electricity
• Reflect light – shiny (luster)
• Solid at room temp (except
Mercury Hg is a liquid at room
temp)
• Malleable – can be
hammered or rolled into
sheets
• Ductile – Can be drawn into
wires
Bonding in Metals – Ionic Bonds
• Generally have 1-3 valence
electrons in outer shell
• Metals tend to give up
electrons easily because of
strength of charge of protons
in nucleus
• Metals + Nonmetals
• Atoms of metals lose
electrons to atoms of
nonmetals
• Both atoms become more
chemically stable when they
form ions
• Take on electron structure of
nearest noble gas
Bonding in Metals – Metallic Bonding
• Positively charged metallic
ions are surrounded by a
cloud of electrons
• Outer-level electrons are not
held tightly to the nucleus of
an atom
• Electrons move freely among
many positively charged
electrons
• Electrons form a cloud around
metal ions
• Explains many properties of
metals1
• 1. Malleable, ductile – metal
does not break because ions
are in layers that slide past
one another without losing
attraction to electron cloud
• 2. Good conductors of
electricity because outer-level
electrons are weakly held
Nonmetals
• Recognize Hydrogen as a nonmetal
• Compare and contrast properties of the halogens
• Describe properties and uses of the noble gases.
Nonmetals
• Usually gases or brittle solids
at room temp
• Not malleable
• Not ductile
• Not shiny
• Most are not good conductors
of heat or electricity
• Most of the human body is
made up of Oxygen, Carbon,
Hydrogen, Nitrogen
• Calcium (metal) makes up 4%
of body
• Phosphorus, Sulfur, Chlorine
• CHNOPS – biologically
important elements
Bonding in Nonmetals
• Ionic Bonds
• Nonmetals + Metals
• Nonmetals become negative
ions
• Metals become positive ions
• Potassium Iodide (KI)
• Nonmetal I becomes neg (I-)
• Metal K becomes pos (K+)
• Covalent Bonds
• Nonmetal + Nonmetal
• Atoms share electrons
• Ammonia, NH3
• Carbon Dioxide , CO2
Alkali Metals
Li, Na, K, Rb, Cs, Fr
• Softer than other metals
• Most reactive – react violently
with oxygen and water
• Don’t occur in nature in
elemental form (stored under oil
or gas)
• One electron in outer shell
• Electron is given up when
bonded
• Alkali metal becomes positively
charged ion
• Ionic forms of sodium (Na+) and
potassium (K+) are critical to
human health
• Lithium (Li) treats bipolar
disorder
• Radioactive element – nucleus
breaks down, gives off particles
and energy
• Francium (Fr) very rare and
radioactive
Alkaline Earth Metals
Be, Mg, Ca, Sr, Ba, Ra
• Combine so readily with other
elements that they are not
found as free elements in
nature
• Two electrons in outer energy
level
• Electrons given up when
bonding to nonmetal
• Becomes positively charged
ion (Ca2+)
• Magnesium (Mg) – Fireworks,
light but strong metal,
chlorophyll is a Mg compound
• Calcium (Ca) – makes bones
strong, muscle contraction,
nerve transmission
• Barium (Ba) – used in
diagnostic medical testing of
digestive system
Transition Elements
Groups 3 - 12
• Iron Triad – Iron (Fe), Cobalt
(Co), Nickel (Ni) – create
steel
• Coinage Metals – Gold (Au),
Silver (Ag), Copper (Cu) –
coins, jewelry, copper wiring,
photographic film
• Zinc (Zn), Cadmium (Cd) –
coat or plate other metals for
protection, rechargeable
batterie
• Mercury (Hg) – silvery, liquid
metal at room temp
• Thermometers
• Bioaccumulates in fish and
can cause mercury poisoning
in people
Inner Transition Metals
Lanthanides
Actinides
• Lanthanum (La), cerium (Ce),
praseodymium (Pm),
samarium (Sa)
• compound used expensively
in the motion picture industry
• Radioactive, unstable
• Thorium (Tm) – used for
making glass in high-quality
camera lenses because it
bends light without much
distortion
• Uranium (U) – nuclear
reactors, weapons,
photographic toner
Nonmetals - Hydrogen
• 90% of all atoms in universe
are Hydrogen
• Most is found in compound
H2O
• Hydrogen = “water forming”
• Diatomic molecule – consists
of two atoms of the same
element in a covalent bond
• Highly reactive – single
electron shares in covalent
bonds
• Hydrides - Can gain an
electron when it combines
with alkali metals and alkali
earth metals
• Sodium Hydride NaH
Nonmetals - Halogens F, CL, Br, I, At
• Halogen lights – Br, I
• Very reactive in elemental
form
• Fluoride - toothpaste, water
• F most chemically active
• Etch glass, frost lightbulbs
• Chlorine – water disinfectant
• I sublimates
• 7 valence electrons
• Halogen + Metal = Salt (Ionic
Bond)
• NaCl
• Gaseous State – reactive
diatomic covalent molecules
• Colorful
• At has no known use
Nonmetals
Noble Gases He, Ne, Ar, Kr, Xe, Rn
• Isolated atoms
• Stable – outer energy level
full
• No naturally occurring
compounds known
• Some created in lab
• Stability makes them useful
• Blimps, balloons, neon signs,
electric lightbulbs, lasers
Mixed Groups - Metalloids
• Distinguish among metals, nonmetals and
metalloids
• Describe the nature of allotropes.
• Recognize the significance of differences in
crystal structure in carbon.
• Understand the importance of synthetic
elements.
Mixed Groups - Metalloids
• Group 13 – Boron Group
• Group 14 – Carbon Group
• Group 15 – Nitrogen Group
• Group 16 – Oxygen Group
• Group 17 – Halogens
• Contain metals, nonmetals and metalloids
Properties of Metalloids
• Can form ionic and covalent bonds with other
elements
• Have metallic and nonmetallic properties
• Semiconductors – some metalloids can conduct
electricity better than most nonmetals, but not as
well as some metals
• Located along the stair step…except for
Aluminum (Al) which is a metal
Boron Group 13 - B, Al, Ga, In, Tl
• Boron
• Borax – water softener
and laundry detergent
• Boric Acid – roach
powder
• Aluminum
• Most abundant metal in
earth’s crust
• Soft drink cans, foil
wrap, cooking pans,
siding
• Strong and light – used
in airplanes
Carbon Group 14 – C, Si, Ge, Sn, Pb
• Carbon - nonmetal
• Coal - elemental C
• Many organic and
inorganic compounds
• CO2 – inorganic –
plants use CO2 and
sunlight it to make
C6H12O6
• Organic C compounds
are the building blocks
of life
• All organic compounds
contain carbon, but not
all carbon compounds
are organic.
Carbon Group 14 – C, Si, Ge, Sn, Pb
• Silicon (Si) – metalloid
• Sand (SiO2), rocks, soil
• Structure similar to
diamonds
• Allotropes – different
forms of same element,
different molecular
structures
• Main component of
semiconductors –
elements conduct electric
current under certain
conditions
• Electronics, computers
Carbon Group 14 – C, Si, Ge, Sn, Pb
• Germanium (Ge) –
metalloid also used in
semiconductors
• Tin (Sn) – metal - coats
other metals to avoid
corrosion (tin cans)
• Bronze, pewter
• Lead (Pb) – metal - used
in paint years ago but
toxic
Allotropes of Carbon
• Diamonds – clear, hard crystal - each C bonded to 4
C’s in tetrahedron in strong, crystalline structure
• Graphite – black powder – hexagonal layers of C atoms
that slide over each other – each C bonded to 3 C’s and
4th electron weakly bonded to next layer
• Buckminsterfullerene – buckyballs – soccer ball
shaped – used to make nanotubes (1 billionth of a
meter in diameter)
Nitrogen Group 15 – N, P, As, Sb, Bi
• Share electrons, covalent
bonds
• Nitrogen (N) - Nitrates,
ammonia in fertilizer
• Fourth most abundant
element in body
• 80% air you breathe is
diatomic N2
• Don’t use in N2 form…
must be combined into
compounds like amino
acids
Nitrogen Group 15 – N, P, As, Sb, Bi
• Phosphorus (P) –
nonmetal, three allotypes
• Water softener, fertilizer,
matches, fine china
• Arsenic (As) - toxic
• Antimony (Sb) –
metalloid • Bismuth (Bi) – metal,
Pepto-Bismol
Oxygen Group 16 – O, S, Se, Te, Po
• Oxygen (O) – nonmetal,
• Sulfur (S) – nonmetal
makes up 21% of air
• Selenium (Se) –
• Diatomic O2 – living things nonmetal – multivitamin
on Earth need it for
respiration
• Ozone O3 – protects Earth
from sun radiation
Synthetic Elements
• Some created by smashing existing elements with particles
accelerated in a heavy ion accelerator
• Nuclear reactors, bombs
• Americium in smoke detectors
• Transuranium – anything over 92 protons – not metal, nonmetal
or metalloid
• Synthetic, unstable, disintegrate quickly, radioactive
• Flerovium #114 – only 90 atoms, over 30 sec which is pretty
long…#112 only lasts 0.0003 sec