Life Science
Earth Science
Matter
Aristotle (Greek 335 BC)
EARTH; WIND; FIRE; WATER
Physical Science is a very large branch of science that
deals with the study of matter and energy. It includes both
Physics and Chemistry. Physics is the study of how objects in
the universe move and how they use energy to interact with
each other. Chemistry is the study of what objects in
the universe are made of. The word chemistry comes
from the Latin word “Alchemista” or alchemy. It
deals with particles and how they combine to form
alchemy - middle ages
substances. Energy: ability to do work - make things move;
early chemistry
does not have mass or volume (matter);
changing lead to gold?
described by the things that it does - its interaction with matter
The two most basic substances in the entire universe are
matter and energy.
Why use Greek and Latin words?
Dead languages, but everyone is still familiar with them
Matter is stuff:
takes up space: length or width = 1 dimension – meter (m);
has volume (v) - size of an object 3D, measured in liters (l)
does not move by itself - needs energy to move
mass (m) - amount of matter it has; theoretically could be
measured by counting the particles of an object; measured
by the object’s inertia – its resistance to changing motion
or how hard it is to push (Newton’s first law of motion);
Mass is measured in grams or kilograms (kg)
meter = one ten-millionth of the distance
from the Earth's equator to the North Pole
(at sea level),
Mass is not the same thing as weight because mass is
constant and weight is not. Weight (w) is the force or pull due
to gravity. Since the force of gravity may change depending on
position, weight may also change. Weight is measured in
Newtons (N). Newton’s second law: Force = mass times
N = kg*m/s2
acceleration (F=MA)
pounds (lbs) and slugs (lbF) ? a mass that accelerates by 1 ft/s2 when a force of one
pound-force is exerted on it
Electromagnetism gives matter energy, makes it move, and
makes it feel solid
Matter - 2
Atoms are made of electrons,
protons, and neutrons. All matter is
made of a combination of these particles.
Normally, atoms have equal numbers of
protons, neutrons, and electrons.
Atomos (Greek) – uncutable or indivisible
A charged particle is a particle of matter and a
particle of energy fused together. Protons have a
positive charge (+), electrons have a negative
charge (-), while neutrons are neutral – no
charge. Particles with the same sign repel,
while those with opposite signs attract.
+ and – same amount of energy; signs to show the
location of the particle
Every atom has a center or nucleus where
the protons and neutrons are bonded together. Electrons are
what make chemical reactions and are what bonds one atom to
another atom to make molecules. The electrons move at
specific distances around the nucleus called orbitals, energy
levels, or shells. The closest or inner shell can hold a maximum
of two electrons. The second shell can hold a max of 8
electrons. The third shell
can hold a max of 18
electrons. The fourth shell
can hold a max of 32
electrons.
The electrons do not move in a
circle. They move in a sphere,
keeping the same distance from
the nucleus. But they repel each
other, so no one knows exactly
where they are at any given time.
]
]
fifth shell? The electron shells
actually overlap.
K
L
M
Predicting where electrons are found is one of the greatest achievements in human
history! Think of the technology!
What are electronics?
Matter – 3
The use of electrons to do work!
Since electrons are attracted to the
nucleus, an atom's electrons will fill
inner shells completely first before filling
outer shells. For example, an atom with
8 protons (oxygen) will also have 8
neutrons and 8 electrons. The electrons
will be placed in the following locations:
2 in the first shell and 6 in the second
shell. Another example: an atom with
20 protons (calcium) will also have 20
neutrons and 20 electrons. The electrons will
be placed in the following locations: 2 in the
first shell, 8 in the second shell, and 10 in the
outer third shell. The electrons in the
outermost occupied shell determine the
chemical properties of the atom and how it
sticks to other atoms. It is called the valence
shell. Valence electrons = electrons in outer shell
]
]
]
Atoms are made of mostly empty space.
If the nucleus (middle) of an atom was a car, the electron would
be about the size of a basketball and would be about 20 miles
away from the car. Matter feels solid despite its emptiness
because the electrons are moving and the charges are repelling.
Neutrons are about the same size as protons, but are slightly
larger (proton + electron). An electron is
about 1 / 2000th the size of one proton.
Must fill inner shells before filling outer shells. Mg (12) 2-8-2
Sub-orbitals? SPDF? electron cloud?
Heisenberg’s Uncertainty Principle?
Ben Franklin fly kite with key in thunderstorm?
0-8-4?
Heavier atoms usually have
more neutrons than protons.
Matter – 4
The only difference between one atom
and another is the number of protons in its
nucleus. Each atom is called an element, and
is given an atomic number that relates to its
number of protons. The atomic mass of an
element is the number of protons plus
neutrons. It is usually 2 to 2.5 times the
atomic number.
Properties of an element are classed as
either chemical or physical.
Chemical properties:
Examples: conductivity, reactivity, acidity, flammability
are due to the location of electrons around the atom's nucleus,
mostly the outer electrons - valence electrons
observed with a chemical reaction or chemical change - elements
are combined or separated to form a new substance
does not affect the nucleus; atomic number of each atom does
is given off (exothermic) or
not change in a chemical reaction Heat
Heat is absorbed (endothermic)
compound: substance made from two or more elements
chemically bonded to form a unique substance
Molecule = atoms chemically combined
Physical properties:
When something dissolves, molecules are broken apart from
other molecules. A solution is made when molecules dissolve
Examples: temperature,
magnetism, volume, mass, and density
evenly.
are observed by examining a sample of the pure element
physical change: a substance changes its form or shape but does
not create a new substance Alloy = mixture of metals that can be separated
when melted; brass, steel
mixture: a combination of two or more substances that are not
chemically combined and can be readily separated without
breaking atomic bonds – sand and water, alcohol and water
What about dissolved substances like salt water or sugar water? Is it a mixture or a compound?
Is it an ion? Sometimes solutions can involve a chemical change – an ionic solution.
Matter – 5
Stable elements are atoms that do not readily change,
react, or stick to other atoms. Atoms are stable when:
they have the same number of protons, neutrons, and electrons
their outer electron shell is filled
inert: a substance does not easily undergo chemical reactions
mostly stable elements are inert - don’t change much
Only the Noble Gas family of atoms (helium, neon, argon,
krypton, radon, and xenon) meets both of these. These atoms
do not stick to anything.
Octet rule: atoms of low (<20) atomic number tend to combine in such a way that they each have eight electrons in their valence shells,
giving them the same electronic configuration as a noble gas. The rule is applicable to the main-group elements, especially carbon,
nitrogen, oxygen, and the halogens, but also to metals such as sodium or magnesium.
Reactive elements are atoms that try to change or combine
with other elements. take or give off heat
Reactive elements always combine with other elements,
give off heat in a chemical reaction; Are they found alone in nature?
An ion is a reactive atom with more or
fewer electrons than protons. A
positive ion or cation (+) means fewer
electrons than protons. A negative ion
or anion (-) means more electrons than
protons.
H+ OHIsotopes are reactive atoms with more
or less neutrons than protons. Most
isotopes are radioactive – particles spit
out of the nucleus.
chemical bonding: ionic – give electrons away out shell mostly empty;
covalent – shared electrons; metallic – metals; hydrogen – electrostatic
If the shell is less than half full,
it will give its electrons away
Matter – 6
Elements can also be reactive because of their
electron location. When the outer shells of atoms are not filled
to max, they try to take electrons from other atoms. This is
what makes atoms stick together. Rust (iron) or corrosion (all
other metals) is an example of a reactive element or molecule
(such as water, air, acids) whose outer electron shell is not
filled. It takes electrons from other molecules breaking their
the shell is more than half full, it will
bonds in order to fill its own outer shell. Iftake
electrons away from other atoms
The + means it is an ion. Which kind?
What about wood and plastic? Do
they corrode? Biodegradable?
The pH scale (power of hydrogen) measures the
concentration of acids (hydrogen ions H+) and the concentration
of bases (hydroxyl ions OH-) in a solution. A solution is where
something is evenly dissolved. Acids and bases must be in a
liquid form. Pure water (H2O) has a pH of 7 and is neutral. Pure
water is neither an acid or a base. Acidic solutions have a low
pH of 0 to >7, while basic solutions have a high pH of <7 to 14.
Basic solutions are also called alkaline. alkaline = basic = base
The - means it is an ion. Which kind?
How much more acidic is orange juice with
a pH of 3 than toothpaste with a pH of 9?
How much more basic is bleach with a pH
of 12 than baking soda with a pH of 9?
Matter – 7
The pH scale is a logarithm scale which means each number
is 10 times greater than the next number. For example, lemon
juice which has a pH of 2 is ten times more acidic than vinegar
which has a pH of 3, 100 times more acidic than tomato juice
which has a pH of 4, and 1000 times more acidic than black
coffee which has a pH of 5.
1 - 2 10
3 - 4 - 5 -
6 -
7 -
8 -
9 - 10 - 11 - 12 - 13 - 14
100 1,000 10,000 100,000 1,000,000
Acids steal electrons from molecules breaking their bonds.
They taste sour and are identified by a red color on blue litmus
paper. Bases give electrons away breaking molecular bonds.
They taste bitter, feel slippery, and are identified by the color
blue on red litmus paper. Both acids and bases conduct
electricity and change the color of other molecules. When
mixed, they trade electrons, may neutralize if the cations and anions
concentrations are equal, and form salt plus water.
pH - power of hydrogen
electrolytes? Salts?
A buffer is a solution that resists change in pH. If you add
an acid, base, or water to a buffered solution, its pH will not
change much. Many life forms thrive only in a relatively small
pH range so they use a buffer solution to maintain a constant
pH. One example of a buffer solution found in nature is blood.
Matter – 8
The elements are grouped according to their chemical and
physical properties. One major classification is as metals,
nonmetals, and metalloids. There are more metals than any
other type of element, but nonmetals make up all life as we
know it.
88 metals+ 18 nonmetals+ 7 metalloids
What is the only metal that is a liquid at room temperature?
Metals are good conductors of both electricity and heat.
They are usually shiny, have high melting points, are solids at
room temperature, and are malleable (able to be hammered or
pressed permanently out of shape
without breaking or cracking) and
ductile (able to be pulled or
stretched into thin wire without
breaking). An alloy is a physical
combination of different metals that
has properties of both.
alloy: mixture - steel, brass
If something is a good electrical conductor, it will allow
electricity/electrons to pass through it without melting or
catching on fire. If something is a good electrical insulator, it
will block or slow down electricity. If
something is a good thermal conductor,
it will allow heat to pass through it
without melting or catching on fire. If
something is a good thermal insulator, it
will block or slow down heat.
Conductivity is measured in micromhos per centimeter (µmhos/cm) or
microsiemens per centimeter (µs/cm). Resistance is measured in Ohms Ω.
Metals have lots of valence electrons, so they can
skip through the outer shells with burning or
melting the material.
Is water a conductor or insulator? BONUS QUESTION
Electrical or thermal? Thermal insulator!
electrical - depends on what you compare it to.
salt water is an excellent conductor
Matter – 9
Most nonmetals are gasses at room
Material
temperature. In their solid state they are
Silver
usually brittle (they break rather than
Stainless steel
bend) and they are insulators of both
Standard
glass
heat and electricity. Wood and plastic
Concrete
Red brick
are nonmetal compounds that are
Water
insulators. Carbon is a nonmetal (atomic Polyethylene
(plastic)
number 6) element that is found in every
Wood
Polystyrene
living thing. A whole branch of science
Air
called Organic Chemistry studies how
carbon works.
What elements could be the basis of all life?
and
polymer - long chains (many units)
Thermal
Conductivity
(W·m−1·K−1)
429
16
1,05
0,9–2
0,69
0,58
0,42–0,51
0,04–0,12
0,03
0,024
Why?
Metalloids are partly like metals and partly like nonmetals.
Most are semiconductors, which means that they conduct
electricity under some
conditions but not others.
Silicon is a very useful
2
metalloid. SiO
silicon + oxygen = glass
or quartz
Dmitri Mendeleev, a
Russian chemist, is generally
silicon
germanium
given credit for developing
the first periodic table in 1869. The modern Periodic Table of
Elements is a chart that lines up the known
elements in order of increasing atomic
number and their electron locations.
Element 101 is named after him.
Hydrogen is one of the most reactive element while helium is one of the
most stable elements.
Matter – 10
In the periodic table there are 7 horizontal rows called
periods that align elements by their electron shells. There are
18 vertical columns called groups or families that align elements
by their outer electron numbers and their similar chemical
properties. Except for
group 18, elements on the left side or
+1
right side of the
+2
-3 -2 -1
table tend to be
more reactive
+3
(they chemically
bond with more
elements) than
elements in the
middle which
are more stable.
The Alkali Metal family (group 1, except for
hydrogen) has elements that are very reactive and
readily form compounds but are not found free in
nature. They form salts and alkali (acidneutralizing) compounds such as baking soda. In
pure form, they are very soft metals which catch
fire on contact with water. Some examples are
lithium, sodium, and potassium.
cutting sodium
with a pen knife;
sodium floats on
water
potassium
reacting with
water
lithium floating in oil
Matter – 11
The Alkali Earth Metal family (group 2) has elements that
are reactive and readily form compounds but are not found free
in nature. In pure form, they are soft and somewhat brittle
metals. Some examples are magnesium and calcium.
pure calcium is
dark colored
magnesium ribbon
on fire
Transition Metals (groups 3 through 12)
are typical metals. They are strong, shiny,
malleable, flexible, and they conduct both
heat and electricity. Some examples are
titanium, copper, iron, zinc, silver, and gold.
Only 3 naturally occurring elements are magnetic: iron (26),
cobalt (27),and nickel (28)
titanium is
super light
Gadolinium (64) and Dysprosium (66) are magnetic under
certain conditions
A neodymium magnet is a permanent magnet made from
an alloy of neodymium (60), iron (26) and boron (5)
Matter – 12
The Halogen family (group 17) are highly reactive
nonmetals that readily form compounds, but are not
found free in nature. They combine with alkali metals to
form salts. Halogen means salt-former. Chlorine is a
poisonous greenish-yellow gas that is used in
disinfectants. When combined with sodium, a poisonous
metal, table salt is formed.
The Noble Gases family (group 18 -helium,
neon, argon, krypton, and xenon, and radon) has
elements that are inactive, or inert. Each atom has
exactly the number of electrons it needs to have a
full outer shell, so these atoms almost never bond
with other atoms. That is why these are all gases.
Neon is used in advertising signs. Argon is used in
light bulbs and welding. Helium is used in balloons
and to cool things. Xenon is used in headlights for new cars.
Radon is radioactive and is sometimes produced in rocks.