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- What are the objects around us
- The properties of matter
Method:
Determine the density of irregular solids as follows:
- Measure and record the mass of one of the irregular
solids.
- Tie a piece of thread around the solid.
- Pour some water into a 100 ml graduated cylinder and
record the volume.
- Gently lower the solid into the water, keeping hold of
the thread. Record the combined volume of the solid and the water.
- Determine the volume of the solid by subtracting the
combined volume from the original volume of the water only.
- Repeat these steps for the second object.
- Complete the table below.
Solid |
Mass (g) |
Volume (ml) |
Density (
) |
Solid 1 |
|
|
|
Solid 2 |
|
|
|
Solid 3 |
|
|
|
Summary
- The smallest unit of matter is the
atom . Atoms can combine to form
molecules .
- A
molecule is a
group of two or more atoms that are attracted to each other by chemical bonds.
- A
small molecule consists of a few atoms per molecule. A
giant
molecule consists of millions of atoms per molecule, for example
metals and diamonds.
- The structure of a molecule can be represented in a
number of ways.
- The
chemical formula of a molecule is an abbreviated way of showing a molecule, using the symbols forthe elements in the molecule. There are two types of chemical formulae:
molecular and empirical formula.
- The
molecular
formula of a molecule gives the exact number of atoms of each element
that are in the molecule.
- The
empirical
formula of a molecule gives the relative number of atoms of each
element in the molecule.
- Molecules can also be represented using
diagrams .
- A
ball and stick diagram is a 3-dimensional molecular model that uses 'balls' to represent atomsand 'sticks' to represent the bonds between them.
- A
space-filling
model is also a 3-dimensional molecular model. The atoms are
represented by spheres.
- In a molecule, atoms are held together by
chemical bonds or
intramolecular forces . Covalent bonds, ionic bonds and
metallic bonds are examples of chemical bonds.
- A
covalent bond exists between non-metal atoms. An
ionic bond exists between non-metal and metal atoms and a
metallic
bond exists between metal atoms.
-
Intermolecular
forces are the bonds that hold
molecules together.
- The
kinetic theory of
matter attempts to explain the behaviour of matter in different
phases.
- The kinetic theory of matter says that all matter is
composed of
particles which have a certain
amount of
energy which allows them to
move at different speeds depending on the
temperature (energy). There are
spaces between the particles and also
attractive
forces between particles when they come close together.
- Understanding chemical bonds, intermolecular forces and
the kinetic theory of matter can help to explain many of the
macroscopic properties of matter.
-
Melting point is the
temperature at which a
solid changes its
phase to become a
liquid . The reverse
process (change in phase from liquid to solid) is called
freezing . The stronger the chemical bonds and
intermolecular forces in a substance, the higher the melting point will be.
-
Boiling point is the
temperature at which a liquid changes phase to become a gas. The stronger thechemical bonds and intermolecular forces in a substance, the higher the boiling
point will be.
-
Density is a measure
of the mass of a substance per unit volume.
-
Viscosity is a
measure of how resistant a liquid is to flowing.
Summary exercise
- Give one word or term for each of the following
descriptions.
- The
property that determines how easily a liquid flows.
- The change in phase from liquid to gas.
- A composition of two or more atoms that act as a unit.
- Chemical formula that gives the relative number of atoms
of each element that are in a molecule.
- For each of the following questions, choose the one
correct answer from the list provided.
- Ammonia, an ingredient in household cleaners, can be broken down to
form one part nitrogen (N) and three parts hydrogen (H). This means thatammonia...
- is a
colourless gas
- is not a compound
- cannot be an element
- has the formula N
3 H
- If one substance A has a melting point that is
lower than the melting point of substance B, this
suggests that...
- A
will be a liquid at room temperature.
- The chemical bonds in substance A are weaker than those
in substance B.
- The chemical bonds in substance A are stronger than
those in substance B.
- B will be a gas at room temperature.
- Boiling point is an important concept to understand.
- Define 'boiling point'.
- What change in phase takes place when a liquid reaches
its boiling point?
- What is the boiling point of water?
- Use the kinetic theory of matter and your knowledge of
intermolecular forces to explain why water changes phase at this temperature.
- Refer to the table below which gives the melting and
boiling points of a number of elements and then answer the questions thatfollow. (
Data from
http://www.chemicalelements.com )
Element |
Melting
point |
Boiling point (
C) |
copper |
1083 |
2567 |
magnesium |
650 |
1107 |
oxygen |
-218.4 |
-183 |
carbon |
3500 |
4827 |
helium |
-272 |
-268.6 |
sulphur |
112.8 |
444.6 |
- What state of matter (i.e. solid, liquid or gas) will each of
these elements be in at room temperature?
- Which of these elements has the strongest forces
between its atoms? Give a reason for your answer.
- Which of these elements has the weakest forces between
its atoms? Give a reason for your answer.
Questions & Answers
I'm interested in biological psychology and cognitive psychology
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How can I develope my cognitive domain
why is communication effective
Communication is effective because it allows individuals to share ideas, thoughts, and information with others.
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miss
Every time someone flushes a toilet in the apartment building, the person begins to jumb back automatically after hearing the flush, before the water temperature changes. Identify the types of learning, if it is classical conditioning identify the NS, UCS, CS and CR. If it is operant conditioning, identify the type of consequence positive reinforcement, negative reinforcement or punishment
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Wekolamo
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ARC
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Skinner skipped the whole unconscious phenomenon and rather emphasized on classical conditioning
war
explain how nature and nurture affect the development and later the productivity of an individual.
nature is an hereditary factor while nurture is an environmental factor which constitute an individual personality. so if an individual's parent has a deviant behavior and was also brought up in an deviant environment, observation of the behavior and the inborn trait we make the individual deviant.
Samuel
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Jonathan
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interpersonal relationships
What would be the best educational aid(s) for gifted kids/savants?
treat them normal, if they want help then give them.
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Saurabh
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Source:
OpenStax, Siyavula textbooks: grade 10 physical science. OpenStax CNX. Aug 29, 2011 Download for free at http://cnx.org/content/col11245/1.3
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