Download worksheer format 11-12

Kuala Lumpur, Malaysia
CLASS : VII
NAME :
TOPIC : Understanding Matter
FORMATIVE ASSESSMENT: I
Ref.: SCI7/ FA I/ HD2/16-17
SUBJECT: Physical Science
DATE:
The Atomic Theory of Matter states that matter consists atoms that make up the molecules.
The Quantum Theory states that the particles of matter can also be in the form of waves.
Everything in this universe is made up of material which scientists have named “matter”. Matter is
anything that has mass and occupies volume. All the things we come across in our daily life are
matter.
It can be a water drop or a cup of tea or ice. Matter is made up of particles, like sand, sugar, salt.
The particles of matter are very small, smaller beyond our imagination. Matter is made up of atoms
and molecules .Atom is the smallest unit which cannot be divided further into smaller particles .
Billions and billions of atomic particles are clubbed together to form the matter that we see around
us. These atoms combine together to form molecules. For example, in water we have two atoms of
Hydrogen combining with one atom of Oxygen to form one molecule of water. Atoms have subatomic particles like protons, electrons and neutrons with protons and neutrons embedded inside
the core of the nucleus and electrons orbit around the nucleus.
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States of Matter
The clouds are made up of matter, the earth is made up of matter. Matter also has states, such as
being solid, liquid, gas, plasma and a new one called Bose-Einstein condensates.. As of 1995,
scientists have identified five states of matter.Matter can change states as well as participate in
chemical changes, depending on their chemical properties and composition.
5 States of Matter
The Five States of Matter are:
1.
2.
3.
4.
Solid
Liquid
Gases
Plasma
5. Bose-Einstein condensate.
1. Solid State
Out of the three states of matter, solids are more common than liquid and gas. The main point in
which a solid differs from the other two states is the fact that gases and liquid possess fluidity i.e.
they can flow and are described as being fluid, while solids do not possess fluidity; instead they are
rigid in nature. The rigidity of solids is due to the presence of strong intermolecular force between
their constituent particles. Hence particles are not free to move and they oscillate at their fixed
positions only. Because of rigidity, solids have a definite shape and volume. Hence solid can be
defined as the state of matter which possesses rigidity, definite shape and definite volume. For
example; A bar of steel, Wood block.
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2. Liquid State
The liquid state lies between the two extremes of ordered arrangement of solids and disorder in
gases. The close packed structure of solids exists to some extent in the liquid state also. But liquid
exhibits only a short range of ordered arrangement and is also termed as condensed gas or molten
solids. In liquid state, the molecules are not as rigid and fixed as in solids.
They have some extent of freedom of motion, because of which they have a definite volume but no
definite shape. Liquid state is much less compressible and far denser than a gas. The
intermolecular force of attraction is only temporary in liquid state which allows it to move freely
resulting in a limited degree of particle mobility.
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2. Gas State
The main difference between gas and other states is that gas molecules move around much more.
The random movement of constituent particles in gaseous state is due to negligible
intermolecular force of attraction. Due to this, intermolecular distance between molecules is very
high. They do not have definite volume or shape. Due to very large intermolecular distance,
gaseous state is highly compressible and easily compressed at high pressure for transportation.
Compared to solid and liquid state, the effect of change in pressure and temperature is more on
gaseous particles within a certain volume. Due to random motion in particles, gaseous state shows
diffusion throughout any container.
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4.Plasma State
Plasma is a state of matter in which all matter is ionized and it occurs in the form of ions and
electrons. Since, we know that for the ionization of the element or matter to occur energy is
required to pull the electron from the attraction of the nuclear charge, high energy is required. So for
the ionic state to exist in nature, a very high level of energy is required. The normal temperature
range in which a plasma can exist is around 6000K. But such a high temperature does not exist in
the natural condition. So the plasma state does not occur naturally on earth.
Plasma is considered as the fourth state of matter along with gases, liquids and solids. Plasma is
sometimes considered as the ionized gases. In physics and chemistry the plasma is considered as
the portion of the gas which is ionized. The ionization of the substance can be done by many
modes, not only by heating but also by applying strong electric field coupled with laser or
microwave region.
Like gases, plasma does not have definite shape or volume, they take up the volume and the shape
of the container. It can be considered that plasma state is gaseous state at high temperature and so
it has some of the properties of gases.
5.Bose-Einstein condensate:
At ordinary temperature gas will moving in random direction. These gas molecules will be moving
with different speed depending on the energy they possess. Example: Molecules moving will higher
speed will be possessing higher energy than other molecules which are moving with the lower
speed.
If we cool these molecules we could see that the atoms slow down. Bose and Einstein predicted
that if a gas made of indistinguishable atoms is sufficiently chilled, a significant fraction of the
particles will settle to the lowest energy. That is, atoms can be forced into their lowest energy state
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at a temperature above absolute zero. When particles reach this state, they form a new form of
matter called a Bose-Einstein condensate.
Change of State
Let us see the following example for this:
1. When water is given heat at a certain temperature it starts getting vaporized. This takes
place at constant temperature known as the boiling point. It is nearly 100 0 C at normal
pressure. Water can also be vaporized at a lower temperature by lowering pressure.
2. Ice can be converted into water at a fixed temperature known as melting point which is 0 0 C
at ordinary pressure. If the pressure is increased ice can melt at a lower temperature than
00 C. However, at a given pressure the temperature of the substance remains constant until
the change of state is complete.
3. Similarly steam can be condensed into water and water can be freezed into ice at the
respective temperatures.
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Exothermic and Endothermic reaction
An exothermic process releases heat, and causes the temperature of the immediate surroundings to
rise. An endothermic process absorbs heat and cools the surroundings.
Exothermic processes
Endothermic processes
making ice cubes
melting ice cubes
formation of snow in clouds
conversion of frost to water vapor
condensation of rain from water
vapor
evaporation of water
a candle flame
forming a cation from an atom in the gas
phase
mixing sodium sulfite and bleach
baking bread
rusting iron
cooking an egg
burning sugar
producing sugar by photosynthesis
forming ion pairs
separating ion pairs
A pure substance:

cannot be separated into 2 or more substances by physical or mechanical means

is homogeneous, ie, has uniform composition throughout the whole sample

its properties are constant throughout the whole sample

its properties do not depend on how it is prepared or purified

has constant chemical composition
A mixture:

can be separated into 2 or more substances by physical or mechanical means

displays the properties of the pure substances making it up

its composition can be varied by changing the proportion of pure substances making it up

heterogeneous substances, ones with non-uniform composition throughout the sample, are
always mixtures
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Elements
An element is a pure substance that cannot be decomposed (broken down) into simpler
substances.
Each element has been given a 1 or 2 letter symbol:

the first letter of the symbol is always a capital letter
eg, H for hydrogen, C for carbon, N for nitrogen

if there is a second letter in the symbol it is a lower case letter
eg, He for helium, Ca for calcium, Ne for neon
Elements can be present in nature as solids, liquids or gases.
Liquid Elements
Gaseous Elements
Solid elements
2 elements exist in
nature as liquids:
11 elements exist in
nature as gases:
all other elements exist in
nature as solids, eg:
mercury (Hg)
bromine (Br)
hydrogen (H)
helium (He)
nitrogen (N)
oxygen (O)
fluorine (F)
neon (Ne)
chlorine (Cl)
argon (Ar)
krypton (Kr)
xenon (Xe)
radon (Rn)
lithium (Li)
carbon (C)
sodium (Na)
magnesium (Mg)
aluminium (Al)
silicon (Si)
phosphorus (P)
sulfur (S)
potassium (K)
calcium (Ca)
zinc (Zn)
The atmosphere is mostly made up of the elements nitrogen (~78%) and oxygen (~21%).
Common elements found in the earth's crust are:









oxygen (O)
silicon (Si)
aluminium (Al)
iron (Fe)
calcium (Ca)
sodium (Na)
potassium (K)
magnesium (Mg)
hydrogen (H)
The most common elements found in living things are:






carbon (C)
hydrogen (H)
oxygen (O)
nitrogen (N)
phosphorus (P)
sulfur (S)
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The most common elements found in the universe are:




hydrogen (H)
helium (He)
oxygen (O)
carbon (C)
Compounds
Compounds are pure substances made up of 2 or more elements.
Each compound has a formula showing which elements are present in the compound
Examples of some common compounds are shown below.
compound
name
compound
formula
elements present
water
H2O
hydrogen (H) and oxygen (O)
ammonia
NH3
nitrogen (N) and hydrogen (H)
carbon monoxide CO
carbon (C) and oxygen (O)
carbon dioxide
CO2
carbon (C) and oxygen (O)
sodium chloride
NaCl
sodium (Na) and chlorine (Cl)
sodium hydroxide NaOH
sodium (Na), oxygen (O) and hydrogen
(H)
calcium chloride
calcium (Ca) and chlorine (Cl)
CaCl2
calcium carbonate CaCO3
calcium (Ca), carbon (C) and oxygen (O)
calcium nitrate
Ca(NO3)2
calcium (Ca), nitrogen (N) and oxygen (O)
calcium
phosphate
Ca3(PO4)2
calcium (Ca), phosphorus (P) and oxygen
(O)
calcium sulfate
CaSO4
calcium (Ca), sulfur (S) and oxygen (O)
methane
CH4
carbon (C) and hyrogen (H)
ethanol
C2H5OH
carbon (C), hydrogen (H) and oxygen (O)
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A compound can be decomposed into simpler pure substances.
For example, an electric current can be passed through water to form the elements hydrogen and
oxygen.
Water can be decomposed into hydrogen and oxygen. Water is a compound made up of hydrogen
and oxygen.
Types of mixtures
Homogeneous Solution
Homogeneous solution can be defined as that mixture which is formed by the combination of a
solute in solvent, which cannot be seen as separate entities either by naked eye or through
microscope or ultra-microscope.
A homogeneous solution cannot be separated by physical separation, simple filtration or
even by ultra-filtration.
Air around us is the most common example of homogeneous mixture. Air is composed of many
individual elements like oxygen, nitrogen, hydrogen, ozone and noble gases, compound gases like
carbon di oxide, nitrogen oxides, oxides of sulfur and water vapor.
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Heterogeneous Solution
Heterogeneous solution is the one in which the solute and solvent particles are seen either by
naked eye or by microscope and can be separated by the normal filtration or ultra-filtration.
Heterogeneous solutions are not transparent and they are either translucent or sometimes opaque .
Homogeneous Vs Heterogeneous
Homogeneous solution
Heterogeneous solution
Translucent or opaque solution may settle in
Clear solution. Transparent and will not settle
some cases
Solutes and solvent cannot be separated by
Can be separated by filtration, or
filtration
semipermeable membrane
Light passes through the solution without any
Light is blocked or refracted when passed
obstruction
through the solution
Individual components can be separated only by Individual components can be separated by
fractional crystallization or distillation
physical methods or by filtration
Salt water, air, alloys are examples of
Smoke, milk, muddy water are examples of
homogeneous solutions
heterogeneous solutions
Solutions: Solution is defined as a homogeneous mixture of two or more components.
Solute : It is that component of the solution, which is present in the smaller amount by weight in the
solution.
Solvent : It is that component of the solution, which is present in the larger amount by weight in the
solution. A solvent may be a liquid, solid, or gaseous substance that dissolves another solid, liquid,
or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent.
For e.g. In the figure shown below, some sugar is added in the water .So, solute is
sugar and solvent is water here.
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Suspensions (heterogeneous):
A suspension is a mixture between a liquid and particles of a solid. In this case the particles do not
dissolve. The particles and the liquid are mixed up so that the particles are dispersed throughout the
liquid. They are "suspended" in the liquid. A key characteristic of a suspension is that the solid
particles will settle and separate over time if left alone. An example of a suspension is a mixture of
water and sand. When mixed up, the sand will disperse throughout the water. If left alone, the sand
will settle to the bottom.
Colloids (heterogeneous):
A colloid is a mixture where very small particles of one substance are evenly distributed throughout
another substance. They appear very similar to solutions, but the particles are suspended in the
solution rather than fully dissolved. The difference between a colloid and a suspension is that the
particles will not settle to the bottom over a period of time, they will stay suspended or float. An
example of a colloid is milk. Milk is a mixture of liquid butterfat globules dispersed and suspended in
water. Colloids are generally considered heterogeneous mixtures, but have some qualities of
homogeneous mixtures as well.
Emulsion:
In physical chemistry, mixture of two or more liquids in which one is present as droplets, of microscopic or
ultramicroscopic size, distributed throughout the other.
Properties of Matter
Some common examples of physical properties of matter are:








Physical state
Colour
Odour
Solubility in water
Hardness
Boiling point
Melting point
Density
Some common examples of chemical properties of matter are:






Iron rusts in moist air
Nitrogen does not burn
Gold does not rust
Sodium reacts with water
Silver does not react with water
Water can be decomposed by an electric current.
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