-
Home
- Siyavula textbooks: grade 10
- 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
a general and ongoing rise in the level of prices in an economy
AI-Robot
What are the factors that affect demand for a commodity
differentiate between demand and supply
giving examples
differentiated between demand and supply using examples
Lambiv
how is the graph works?I don't fully understand
hi guys good evening to all
Lambiv
In economics, a perfect market refers to a theoretical construct where all participants have perfect information, goods are homogenous, there are no barriers to entry or exit, and prices are determined solely by supply and demand. It's an idealized model used for analysis,
Ezea
other things being equal
AI-Robot
When MP₁ becomes negative, TP start to decline.
Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 •
Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of lab
Kelo
Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 •
Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of labour (APL) and marginal product of labour (MPL)
Kelo
Can I ask you other question?
Shukri
What is different between quantity demand and demand?
Quantity demanded refers to the specific amount of a good or service that consumers are willing and able to purchase at a give price and within a specific time period. Demand, on the other hand, is a broader concept that encompasses the entire relationship between price and quantity demanded
Ezea
how do you save a country economic situation when it's falling apart
what is the difference between economic growth and development
Economic growth as an increase in the production and consumption of goods and services within an economy.but
Economic development as a broader concept that encompasses not only economic growth but also social & human well being.
Shukri
production function means
Jabir
What do you think is more important to focus on when considering inequality ?
any question about economics?
sir...I just want to ask one question... Define the term contract curve? if you are free please help me to find this answer 🙏
Asui
it is a curve that we get after connecting the pareto optimal combinations of two consumers after their mutually beneficial trade offs
Awais
thank you so much 👍 sir
Asui
In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities, where neither p
Cornelius
In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities,
Cornelius
Suppose a consumer consuming two commodities X and Y has
The following utility function u=X0.4 Y0.6. If the price of the X and Y are 2 and 3 respectively and income Constraint is birr 50.
A,Calculate quantities of x and y which maximize utility.
B,Calculate value of Lagrange multiplier.
C,Calculate quantities of X and Y consumed with a given price.
D,alculate optimum level of output .
Got questions? Join the online conversation and get instant answers!
Source:
OpenStax, Siyavula textbooks: grade 10 physical science. OpenStax CNX. Aug 29, 2011 Download for free at http://cnx.org/content/col11245/1.3
Google Play and the Google Play logo are trademarks of Google Inc.