LECTURE NOTE 4
MATTER AND ENERGY
Matter is anything that has mass and occupies volume. Matter exists in one of the
three physical states: solid, liquid and gas.
PHYSICAL STATES OF MATTER
Property
Shape
Volume
Compressibility
Solids
Fixed
Fixed
Negligible
Particles are tightly
packed, no
movement
Liquid
Variable
Fixed
Negligible
Particles move
freely pass one
another, shape
varies.
Gas
Variable
Variable
Significant
Particles are widely
spaced and
uniformly
distributed
throughout the
container.
Ice → Water→Steam
(Solid changes to water when temperature is raised, water changes to steam when the
temperature is raised to 1000C)
Iron → liquid iron →Gas
(Iron metal changes to liquid iron at 15350C, while liquid iron changes to gas at 27500C)
Solids MELT to ice with increase in temperature.
Liquids FREEZE to ice with decrease in temperature.
Liquids VAPORIZE to gases with increase in temperature.
Gases CONDENSE to liquids when temperature drops.
Solids SUBLIME to gases with increase in temperature.
Gases DEPOSE to solids with decrease in temperature.
The fourth state of matter exists at very high temperature. Under extreme
condition, matter can separate into positive and negative subatomic particles referred to
as PLASMA.
For example, at the surface of the sun, at temperature of about 60000C, hydrogen and
helium exist as plasma. Solar flares are streams of plasma shooting from the surface of
the sun.
ELEMENTS, COMPOUNDS AND MIXTURES
A sample of matter might have properties that are consistent throughout or vary.
The only way to test if the property of matter is consistent is to MELT the sample.
For example, a sample of pure gold melts at 10640C and does not vary, whether it
is large nugget or a small gold flake. Quartz on the other hand melts between 10000C and
16000C, it believed to contain different substances. Therefore, Quartz is said to be
Heterogeneous while gold is said to be Homogenous. Heterogeneous substances have
their properties indefinite and varying while Homogenous substances have their
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properties definite and constant. Heterogeneous mixtures can be separated into pure
substances by physical method.
Examples of homogeneous mixtures:
Salt + water = salt solution
Air = nitrogen + oxygen + other gases.
Homogeneous mixtures may have properties that vary from sample to sample. For
example, samples of sea water, sample from Pacific Ocean differ from sample from Dead
Sea in properties, although they are both sea water. Dead Sea has higher density and
greater concentration of dissolved minerals.
An alloy is a homogenous mixture of two or more metals. An example is 10K,
14K and 18K gold jewelry: all contain gold, silver and copper metals. The amount of
gold varies from 45-75%, in these samples. 10K gold is a harder alloy and is more scratch
resistant than 18K.
A substance is matter that has definite composition and constant properties. A
substance is either a compound or an element.
A compound has predictable properties but can be broken down into elements by
ordinary chemical reaction. For example, table sugar is a compound, and can be broken
down into carbon, hydrogen and oxygen.
An element is a substance that cannot be broken down further by chemical reaction. For
example, table salt is composed of the elements sodium and chlorine, which cannot be
broken down any further.
NAMES AND SYMBOLS OF ELEMENTS.
There are stable elements that occur in nature. Few naturally occurring that are not
stable (uranium), on the whole over 100 elements. 10 of these elements accounts for 95%
of the mass of earth’s crust, water and atmosphere. Oxygen is the most abundant element
in nature:
 21% of atmosphere(uncombined)
 Combines with hydrogen to form water.
 Combines with silicon in sand and rocks.
The three most abundant elements are oxygen, silicon and aluminum (49.5%, 25.7%
and 7.5% respectively) in the earth’s crust, water and atmosphere. The elements oxygen,
carbon, hydrogen, nitrogen, calcium and phosphorus account for over 99% of the mass of
the human body.
Elements
Hydrogen
Carbon
Calcium
Germanium
Scandium
Curium
Nobelium
Chlorine
Uranium
Helium
Sources of names
Greek(water former)
Latin(coal-carbo)
Latin(lime-calcis)
Germany(country)
Scandinavia(country)
Marie Curie(name)
Alfred Nobel(name)
Greek(chloros-greenish yellow)
Uranus(planet)
Greek(helios-sun)
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John Dalton came up with using circles with enclosed markings as symbols for
the elements.
Berzelius proposed our current system of symbols for the elements. He suggested
that a symbol corresponds to the first letter, example, H for hydrogen, C for carbon. In a
case we have more than one of the same letter, the second letter is picked from the name,
example, Ca for calcium, Cd for cadmium and Cl for chlorine. Sometimes the symbols
are derived from their Latin or Greek words, example , Pb for lead (plumbum-Latin).
Others are: gold(Au), silver(Ag), copper(Cu), iron(Fe), mercury(Hg), potassium(K),
sodium(Na), tin(Sn), antimony(Sb) The first letter is in capital while the second letter is
small letter.
Property
Physical state
Appearance
Pliability
Conductivity
Density
Melting Point
Chemical Reactivity
Metal
Solid
Metallic luster
Malleable, ductile
Heat, electricity
Usually high
Usually high
React with non-metals
Non-metals
Solid, gas
Dull
Brittle
Non-conductor
Usually low
Usually low
React with metals and nonmetals
A third group exists called the Semimatals or Metalloids, they exhibit properties of both
metals and nonmetals.
PERIODIC TABLE
Atomic number is the number that identifies a particular element. For example,
atomic number of H is 1, He is 2, and U is 92.
Periodic table is a special chart in which all elements have been arranged by atomic
number. Metals are found on the left hand side while the non-metals are found on the
right hand side with the exception of H. Metals and the non-metals are separated by
semimetals (B, Si) in a zigzag form on the table.
PHYSICAL STATES OF ELEMENT
All the metals are in solid state at normal condition of 250C and normal
atmosphere pressure except Hg which is liquid. Non- metals show diversity state at same
condition.
5 are solids- C, P, S, Se, and I.
1 is liquid- reddish-brown bromine (Br)
11 are gases- H, Ne, N, O, F, Cl, Ne, Ar, Kr, Xe, and Rn. All these are colorless except F
and Cl which are greenish yellow.
COMPOUNDS AND CHEMICAL FORMULAS
Law of definite composition states that: compounds always contain the same
elements in a constant proportion by mass.
Example, NaCl has 39.3% of Na and 60.7% of Cl.
H2O has 11.2% of H and 88.8% of O
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A molecule is a single particle composed of two or more non-metal atoms H2 , O2.
.
Chemical formula- expresses the number of each element in a compound. Number
of atoms is located by the superscript unless it is 1 in which it is omitted. H2SO4 has 2
atoms of H, 1 atom of S and 4 atoms of Oxygen.
Property
Appearance
Sodium
Silver metal
Chlorine
Yellowish gas
Sodium Chloride
Colorless crystal
Melting point
980
-1010
8010
Boiling point
8830
-350
14130
Density
0.97g/cm3
2.90g/L
2.17g/cm3
0.51g at 300
35.7g at 00
Solubility in 100g of React with water
water
PHYSICAL PROPERTIES AND CHEMICAL PROPERTIES
Physical Properties are observed without altering the composition of the substance
while chemical properties always involve a chemical change.
Refer to the example in the textbook for chemical property reactions of elements on the
periodic table.
There is no alteration in composition of substance, while there is formulation of new
substance in the following form:
 Permanent color change.
 Odor or bubbles from release of a gas.
 Light or heat from the release of energy.
Physical Properties
Chemical Properties
Melting of ice to water.
Ripening of banana from green to yellow.
Heat alcohol to vapor.
Antacid tablet dissolves in water, evolves
gases.
Recycling aluminum can into aluminum
Fireworks display a shower of colorful
foil.
lights.
Law of Conservation Mass.
Law of conservation of mass: matter was neither created nor destroyed during a
chemical reaction.
Potential and Kinetic Energy
Energy is the ability to do work. There are types:
 Potential Energy.
 Kinetic Energy
Potential energy is the stored energy that matter possesses as a result of its position
or composition. Kinetic energy is the energy that matter has as a result of its motion.
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KINETIC ENERGY, TEMPERATURE, AND PHYSICAL STATE
When a substance in solid state is heated, the temperature increases and particles
begin to randomly vibrate in fixed positions. As a solid acquires more heat energy,
particles vibrate so intensely that the force of attraction is overcome and the particles
break free of each other. This is a description of the liquid state.
A liquid is therefore a state of matter in which particles possess sufficient energy
to overcome their mutual attraction and have limited movement. When a liquid has
enough to completely overcome the force of attraction, the particles are free to fly about
and strike the walls of the container. At this point, the liquid has changed to the Gaseous
state.
Property of Particle
Kinetic energy
Movement
Solid
Very low
none
Liquid
High
Restricted
Gas
Very high
unrestricted
The six form of energy are heat, light, chemical, electrical, mechanical, and
nuclear. The law of conservation of energy states that energy is neither created nor
destroyed. Energy may be converted, however, from one form to another. In practice,
chemical energy is used to provide heat and electrical energy. The laws of conservation
of mass and conservation of energy can be treated as a single principle- the Law of
conservation of mass and energy. For ordinary chemical reactions, energy changes are
sufficiently small that we can ignore this principle and apply conservation of mass and
conservation of energy individually.
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