Download Chemistry: 4.1Notes

Unit B
Chemical Reactions
4.1: Matter
• Matter is anything that has mass and
takes up space
• Matter does not include any form of
energy, such as light, heat, and sound.
• Many substances have been classified
according their physical and chemical
properties
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B-1
Properties of Matter
• A physical property is a property that describes
the physical appearance and composition of a
substance.
• A chemical property is a property that describes
the ability of a substance to change into a new
substance or substances.
• Check table 4.1 & 4.2 Pg 142
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B-2
Pure Substances and Mixtures
• All forms of matter can be classified as
either a pure substance or a mixture,
based on their physical and chemical
properties.
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B-3
A pure substance
• made up of only one kind of matter.
• has a unique set of properties, such as
colour, hardness, melting point, and
conductivity.
• A pure substance is either an element or a
compound.
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B-4
• An element is a substance that cannot be
broken down into any simpler substance by
chemical means.
• E.g. Iron, oxygen, and neon are examples of
elements.
• A compound is a pure substance that is made
from two or more elements that are combined
together chemically.
• E.g. methane (CH4) contains the elements
carbon and hydrogen.
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B-5
A mixture
• is a combination of pure substances
• Properties of mixtures vary
• Two main types of mixtures
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B-6
Types of Mixtures
• A homogeneous mixture is a mixture that
looks the same throughout and the
separate components are not visible.
• Solutions are homogeneous mixtures.
• iced tea is a solution of sugar and other
substances dissolved in water
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B-7
• A heterogeneous mixture is one in which different
parts of the mixture are visible.
• a suspension, a cloudy mixture in which tiny
particles of one substance are held within another
substance.
• Salad dressing is an example of a suspension
• a mechanical mixture, may contain several solids
combined together, such as in a chocolate-chip
cookie.
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B-8
Classification of Matter Tree Diagram
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B-9
Matter And Atoms
• All matter is made up of tiny particles
called atoms. An atom is the smallest part
of an element that has all the element’s
properties.
• Gold and silver are elements. Atoms of
gold are similar to each other but different
from atoms of silver.
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B - 10
Dalton’s Atomic Theory
• Atomic theory is the study of the nature of atoms and how
atoms combine to form all types of matter.
• Atoms are the smallest indivisible particles of matter
• Each element has its own unique kind of atom.
• Atoms of different elements vary in mass, volume, and
reactivity and are in continuous motion.
• Atoms combine to form compound/molecules
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Subatomic Particles of matter
• There are three subatomic particles, protons, neutrons, and electrons
that make atoms.
• Electrons and protons have an electric charge.
Protons have a positive charge of 1+.
Electrons have a negative charge of 1• Neutrons are neutral.
• The masses of protons and neutrons are almost 2000 times greater
than the mass of electrons
• Copy Table 4.3 Properties of Subatomic Particles
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B - 12
An Atom
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Representing an Atom
• The basic arrangement of the nucleus and electrons
in a atom is typical of all atoms e.g. sulphur.
• The atoms of every element have a unique number
of protons, called atomic number.
• A Bohr-Rutherford diagram is an illustration of an
atom that shows the arrangement and number of
electrons in each shell, with number of protons and
neutron in the nucleus .
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Bohr-Rutherford Diagram
• The electrons surround the nucleus in shells.
Each shell has a specific energy level.
• The innermost shell can hold two electrons
at most.
• The next two shells can hold up to eight
electrons each.
• The outermost shell of an atom is called the
valence shell and contains the valence
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electrons.
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Sulphur Atom
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Bohr Diagrams of First 20 Elements from the Periodic Table
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The Periodic Table of Elements
• The periodic table contains a set of symbols to
represent the elements, laid out in a specific
pattern
• Dmitri Mendeleev was the first person to
create a table that organized all the elements
logically, including those that were not
discovered at the time.
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Characteristics of the Periodic Table
• The horizontal rows of the periodic table are called
periods.
• The vertical columns are called families (or groups).
• Elements in the same family in the periodic table
have similar physical and chemical properties
• Metals are on the left and in the centre of the table.
• Non-metals are located on the right-hand side of the
table.
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• Metals are separated from non-metals by a
staircase of elements called the metalloids.
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Metals and non Metals
• Metals are good conductors of
heat and electricity.
• they are ductile and malleable.
• they are shiny and usually
silver coloured, and all but one
are solids at room
temperature.
• Nonmetals are not metals, and
they generally are poor
conductors of heat.
• At room temperature, some
non-metals are solids, some
are gases, and one, bromine,
is a liquid.
• Mercury is a metal, but it is
liquid at room temperature.
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Dmitri Mendeleev
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Periodic Table
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Chemical Families
• alkali metals (group 1):metals that react easily with
water and with oxygen in the air.
hydrogen is not an alkali metal
• alkaline earth metals (group 2): harder and less
reactive than group 1 metals. combines easily with
other atoms.
• halogens (group 17): most reactive non-metals
• noble gases (group 18): unreactive gases does not
combine easily with other atoms.
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Chemical Families from the Periodic Table
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Elements on the Periodic Table
• The atomic number: is the number of protons
in an atom of an element. E.g. atomic number
of copper is 29
• The atomic mass is the average mass of an
atom of that element. atomic mass of hydrogen
is about 1, copper is 63.55.
• mass of a copper atom is about 64 times the
mass of a hydrogen atom.
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Ion Charge:
• An ion is an atom or group of atoms with a
negative charge or a positive charge.
• Atoms of some elements can gain or lose electrons
during chemical change.
• An atom that gains electrons becomes a negatively
charged ion.
• An atom that loses electrons becomes a positively
charged ion.
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Copper from the Periodic Table
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