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Physical States of Matter
Solid: Definite shape and definite volume
Particles tightly packed, held in rigid positions
Can not be compressed
Liquid: Variable shape and definite volume,
Particles loosely packed, move freely, compress slightly
Gas: Variable shape and Variable volume.
Particles move freely and Can be easily compressed
*Iron becomes liquid at 1535-3000 oC and gas >3000 oC
*Water exists in all three forms under natural conditions
States of Water
Physical changes
Gas
Sublimation
Deposition
Condensation
Evaporation
Melting
Solid
Liquid
Freezing
Elements, Compounds, and Mixtures
Heterogeneous Mixture: It can be separated into
pure substances by physical methods. The properties
are not constant
Ex: Quartz rock is a heterogeneous mixture of gold
and sand. They can be separated by difference in
their density.
Homogeneous mixture can also be separated by
physical methods. The properties of given sample are
constant. However, the properties may vary from
sample to sample.
Mixtures
Alloy: It is a homogeneous mixture of two or
more metals
Ex: Gold is gold, silver and copper. The
percentage gold varies in 10K, 14K and 18K (4275%
Substance: It is a matter that has definite
composition and constant properties. A
substance can be an element or a compound
Elements and Compounds
Element: It is substance that can not
be separated or broken down further
by chemical or physical methods.
Compound: It contains two or more elements
that can be broken into pure elements by
chemical method.
Ex: Sugar can broken down into Carbon,
Hydrogen and Oxygen by chemical method
Elements and Compounds
Elements, Compounds and Mixtures
Genesis of Names and Symbols of Elements
1) Over 100 elements are present
2) Only 10 elements account of 95% of the mass
of earth
3)
Earth: 49.5% Oxygen, 25.7% Silicon,
7.5% Aluminum, 4.7% Iron, 3.4% calcium,
9.2% other elements
Names and Symbols of Elements
Hydrogen: A Greek word meaning water former
Carbon: Latin word Carbo, meaning coal
Calcium: Derived from Latin word calcis, (lime)
Germanium: Germany
Scandium: Scandinavia
Curium: Marie Curie (scientist)
Nobelium: Alfred Nobel
Names and Symbols of Elements
John Dalton’s Proposal: Elements are composed
of indivisible, spherical particles, called as atoms
(Greek word atomos meaning indivisible)
Names and Symbols of Elements
IN 1813, J.J. Berzelius proposed the current system
Berzelius Proposal:
1) A symbol corresponds to the first letter of the
name of the element
Ex: H, C, O
2) When the elements start with the same letter,
two letters from the name should be used as
symbol. Ex: Ca, Cd, Cl
Symbols from Latin names
Pb: for Lead, Latin name is plumbum
Hg: Mercury, Latin name Hydrargyro
(liquid silver)
Au (Gold), Na (Sodiuim), K (Potassium),
Sb (Antimony), Sn (Tin),
Cu (Copper), Fe (Iron)
Conventional writing of symbols
The first letter should always be
capitalized and the second should in
lowercase.
Ex: Co (Cobalt
Periodic Table of the Elements
All the elements have been arranged by atomic number
a) B, Si, Ge, As, Sb,Te,Po, At are semimetals
b) H, C, N, O, F, Ne, P, S, Cl, Ar, Se, Br, Kr, I, Xe, Rn
are nonmetals
c) Hg, Br are liquids
Metals, Nonmetals and Semimetals
A metal is an element, typically a solid, has a bright
metallic luster, high density, high melting point and is
a good conductor of heat and electricity.
A metal can be hammered into a thin sheet of foil
(malleability)
If a metal can be drawn into a fine wire, it is said to be
ductile. Ex: Aluminum, copper and silver
Nonmetals
Low density
Low melting point
Poor conductors
Occur in mostly solid and gaseous state
Solids are neither malleable nor ductile
General characteristics of Metals and Nonmetals
PROPERTY
Metals
Nonmetals
Physical state
Solid
Solid, gas
Appearance
Metallic luster
Dull
Pliability
Malleable, ductile
brittle
Conductivity
Heat and electricity Nonconductor
Density
Usually high
Usually low
Melting point
Usually high
Usually low
Chemical reactivity
React with
nonmetals
React with metals
and nonmetals
Semimetals
Semimetals are called metalloids. Properties are
midway between metals and nonmetals.
Ex: Silicon is a semiconductor, used in transistors
and integrated circuits.
Physical state of Elements
All the metals, except Mercury, are solids.
All the semimetals are also in solid state
Nonmetals show great diversity. At 25 oC, and normal
pressure, five nonmetals are solids, one is liquid and
eleven are gases.
Compounds and Chemical formulas
Compounds always contain the same elements
in a constant proportion by mass
-French chemist Joseph Louis Proust
Example:
NaCl contains 39.3% Sodium and 60.7% Chlorine
Water contains 11.25% Hydrogen, 88.8% Oxygen
Compounds and Chemical formulas
The number of atoms is indicated with
subscript, unless the number is 1
Ex: H2O, NH3, O2, H2, Cl2
Chemical formulas
Some chemical formulas use
parentheses to clarify chemical
composition
C2H4(OH)2
Vitamin B
Vitamin B3: C6H6N2O
Vitamin B6:
8 Carbon atoms
11 Hydrogen atoms
1 Nitrogen atom
3 Oxygen atoms
Write the formula
Properties of Matter
*Properties are the distinguishing characteristics
of a substance that are used in its identification
and description
* Each chemical substance has a unique set of
properties that distinguishes it from other
substances
Physical and Chemical properties
Physical property: Characteristic of a substance
that can be observed without changing the
substance into another substance
Ex: Color, odor, taste, size, physical state, density, melting point
and boiling point
Chemical property: Characteristic of a substance
that describes the way it undergoes or resists
change to form anew substance
Ex: Rusting nails is chemical property of iron
Chemical properties
*Changes associate with chemical properties
result from the interaction of a substance with
one or more other substances
*Sometimes the presence of energy (heat, light)
and pressure also triggers the change. (ex:
decomposition of Hydrogen peroxide into water
and oxygen)
Physical and chemical properties of Water
Physical
1) Colorless
2) Odorless
3) Boiling point = 100 oC
4) Freezing point = 0 0C
5) Density = 1.000g/ml at 4 oC
Chemical
1) Reacts with bromine to form a mixture of
two acids
2) Can be decomposed by means of electricity
to form hydrogen and oxygen
3) Reacts vigorously with sodium metal to
produce hydrogen
4) Does not react with gold even at high
temperatures
5) Reacts with carbon monoxide at elevated
temperature to produce carbon dioxide
Intensive and Extensive properties
Intensive property: A property that is
independent of the amount of substance
Ex: Temperature (boiling and melting points),
color, density and all chemical properties
Extensive property: A property that depends on
the amount of substance
Mass, Volume, length
Changes in Matter
Physical change: It is a process in which a
substance changes its physical appearance but
not chemical composition. Ex: NaCl in water
Chemical Change: It is process in which a
substance undergoes a change in chemical
composition
Irreversible and original substance can not be
recovered
Gray areas
1) Hydrochloric acid in water cannot
be recovered
2) Cooking of an egg
Change
Rusting of iron
Melting of snow
Digesting food
taking a bite of food
Burning gasoline
Slicing an anion
Detonation of dynamite
Souring milk
Breaking of glass
Classification
Chemical
Physical
Chemical
Physical
Chemical
Physical
Chemical
Chemical
Physical
Conservation of Mass
Law of conservation of mass (By Antoine Lavoisier, 1789)
“Matter can be neither created not destroyed”
If 1g Hydrogen combines with 8g of Oxygen, the resulting water
will be 9g
If 9g water decomposes, it will produce 1g Hydrogen and 8g
oxygen.
2.430g of Magnesium was burned with oxygen to give 4.030g of
Magnesium oxide powder.
What is the mass of Oxygen?
Potential Energy and Kinetic Energy
Potential Energy: The energy that mater possesses
as a result of its position or composition
Kinetic Energy: The energy matter has as a result of
its motion.
Properties and physical states
As the temperature increases, the kinetic energy of
matter increases.
Property of particle Solid
Liquid
Gas
Kinetic Energy
Very low
High
Very high
Movement
Negligible
Restricted
Unrestricted
Conservation of Energy
Law of conservation of energy: Energy can not be
created nor destroyed. Energy can be converted from
one form to another
1g of water requires 540 cal to become steam.
When steam cools down to become water, it
releases 540 cal energy
Heat of energy absorbed
1g water + 540 cal
100 C
Heat of energy released
1g steam
Energy and chemical changes
Energy absorbed
Water + electrical energy
Hydrogen + Oxygen
Energy released
Hydrogen + Oxygen
Water + Heat energy
Forms of Energy
Heat
Light
Chemical
Electrical
Mechanical
Nuclear
All forms of energy are convertible
Ex: Solar panels (Light to electrical)
Turbine spins and drives an electrical generator
(Mechanical to electrical)
Conservation of mass and energy
E = mc2
Energy E and mass (m) are related by the velocity of
light (c)
Total mass and energy in the universe is constant
Application in chemistry
In a chemical reaction, the law indicates that the total
mass and energy before and after a chemical change
is constant.