Transcript Unit1: Matter Review

Unit1: Matter
Review
General Properties of
Matter
• Matter is anything that
has mass and volume
• Everything is made of
matter
General Properties of
matter
• Mass, weight, volume,
and density
• Properties are used to
identify a substance
States of matter
• Four states of matter: solid,
liquid, gas, and plasma
• solids have a definite shape
and volume
• Solids are tightly packed and
the particles vibrate
Physical Properties of Matter
• Hardness – a measure of the resistance
of a solid to being scratched or dented.
• Malleability – When a solid can be
hammered into sheets or bent into
shapes.
• Ductility – solid can be pulled into
wires.
• Crystal form – when a definite structure
of blocks or cubes in a regular pattern
form.
Physical Properties of Matter
• Solubility – the ability of a substance to
dissolve in a solvent.
• Viscosity – refers to how easily a liquid
flows.
• Density – the amount of matter per unit
volume of that matter. Usually
expressed in grams per cubic
centimeter (g/cm3).
Chemical Properties
• A chemical property is a behavior of a
substance when it interacts with another
substance. This usually forms a new
substance.
• Combustibility – describes the ability of a
substance to react with oxygen to produce
carbon dioxide, water and energy. If a
substance is combustible or flammable, it
will burn when exposed to a flame.
Physical Change
• In a physical change, the substance
involved remains the same substance.
• Changes of state – melting, boiling,
freezing, condensation, sublimation –
are all physical changes.
• Dissolving is also a physical change.
• Most physical changes are easy to
reverse.
Chemical Change
• In a chemical change, the original
substance is changed into one or more
different substances that have different
properties.
• Chemical changes always involve the
production of new substances.
• Chemical changes are difficult to
reverse.
• Examples include burning, cooking and
rusting.
How can you tell if a change is
chemical or physical?
• There are many signs that can tell us.
Consider several clues before coming to a
conclusion.
1. A new color appears
2. Heat or light is given off
3. Bubbles of gas are formed
4. A solid material (called a precipitate)
forms in a liquid.
5. The change is difficult to reverse.
Chapter 2
The Particle Theory of Matter
1. All matter is made up of tiny particles.
2. All particles of one substance are the
same. Different substances are made up of
different particles.
3. The particles are always moving. The
more energy the particles have, the faster
they move.
4. There are attractive forces between the
particles. These forces are stronger when
the particles are closer together.
•As well as classifying matter as solids,
liquids, and gasses, we can classify matter
as either a mixture or a pure substance.
•A pure substance is made from only one
type of particle. These specific particle
types give the substance its physical
characteristics such as odor, color,
hardness.
•A mixture contains two or more pure
substances. (See Fig. 1 pg. 45)
• A homogeneous mixture has two substances
where the particles are blended completely.
To the eye, the mixture appears to be pure
substance.
• When the particles
stay intermixed and
don’t settle into
layers we call the
homogeneous
mixture a solution.
•A heterogeneous mixture has large clumps of
particles that don’t fully separate and get
intermixed with the other substance.
•Examples of heterogeneous mixtures are salad
dressing, oil and water, pizza, etc.
Elements and Compounds
• Elements are pure substances that
cannot be broken down into simpler
substances.
• Compounds are pure substances that
contain 2 or more elements in a fixed
proportion. They are formed when
elements combine together in
chemical reactions.
What makes up an atom?
• Three types of particles make up an
atom; these are called subatomic
particles.
• Protons – positive charge, found in the
nucleus.
• Neutrons – no charge, found in the
nucleus.
• Electrons – negative charge, found
orbiting the nucleus.
Chemical Symbols
C
Carbon
Cu
Copper
• All elements have their
own unique symbol.
• It can consist of a single
capital letter, or a
capital letter and one or
two lower case letters.
Chemical Formulas
• When atoms of different elements combine,
they form compounds.
• A chemical formula is the combination of
symbols that represents a particular
compound. (Table 2 pg. 59).
• If there is more than one atom of the
element in a compound, the symbol is
followed by a number (called a subscript).
• Eg. H2O = Water (2 atoms of Hydrogen
and 1 atom of oxygen)
How can we determine the
charge of an ion?
• For some of the elements it is very easy.
Elements in groups 1, 2, 13, 14, 15, 16, &
17 will lose or gain electrons so they have
the same # as the nearest Noble Gas (group
18).
• The transition metals (groups 3- 12) cannot
have their charges predicted in this way due
to many of them having isotopes. Their
charges must be predicted in other ways.
Rules For Combining Elements
• Rule 1: Metals combine with non metals in
many compounds.
• Rule 2: Write the name of the metal first
and the non metal second.
• Rule 3: Change the ending of the non metal
to “ide.”
• Rule 4: Each atom has its own combining
capacity.
• Rule 5: Atoms combine so that each can fill
its own combining capacity.
• When combining 2 ions, you need to create
a net charge of zero.
• Eg. Ca2+ + ClCaCl2 (2 positives, 2
negatives = 0 charge)
• If you do not know the combining capacity
of the element, you can use your knowledge
of ions. The charge of the ion is it’s
combining capacity.
• Use the following method to then make the
compound
Crossing Over Method
2+
Ca
+
2O
Ca2O2
(2’s cancel out) CaO = Calcium Oxide
2+
Mg
+
Cl
= Magnesium Chloride
MgCl2
Ch. 3
Atomic Models: Dalton
1. All matter is made of atoms, which are
particles that are too small to see.
2. Each element has it’s own kind of atom
with it’s own particular mass
3. Compounds are created when atoms of
different elements link to form
molecules.
4. Atoms cannot be created or destroyed
or subdivided in chemical changes.
Atomic Models: J.J. Thompson
• The atoms are neutral… How?
• + charges must be present to balance charges
• + & - lumped in a cluster he said
looked like “plum pudding”
Rutherford’s Atomic Model
• Rutherford developed a new model for
the atom.
• An atom has a tiny, dense positive core
called the nucleus (which deflected the
alpha particles and contains protons.)
• The nucleus is surrounded mostly by
empty space, containing rapidly moving
negative electrons (through which
alpha particles pass unhindered.)
Atomic Models: Bohr
• Niels Bohr proposed a
“planetary” model of
the atom.
• Electrons are found in
specific energy levels
called orbits
– Like planets around the
sun
Atomic Models: Bohr
• Each electron in an orbit has a definite
amount of energy.
• The further the electron is from the
nucleus, the more energy it has.
• Electrons do not exist between the orbits
but can move from on orbit to another.
• The order of filling of electrons in the first
three orbits is 2, 8, 8.
• Electrons are more stable when they are at
lower energy, closer to the nucleus.
What’s in a square?
• Different periodic
tables can include
various bits of
information, but
usually:
– atomic number
– symbol
– atomic mass
Key to the Periodic Table
• Elements are organized on
the table according to their
atomic number, usually
found near the top of the
square.
– The atomic number refers
to how many protons or
electrons an atom of that
element has.
– For instance, hydrogen
has 1 proton, so it’s
atomic number is 1.
– The atomic number is
unique to that element.
No two elements have the
same atomic number.
Bohr Diagrams
• Bohr’s model was
readily accepted by
scientists and they
began drawing
models of the atom
using his theory.
Bohr-Rutherford Diagrams
• This diagram is a combination of
Rutherford's nuclear model and Bohr’s
planetary model.
• It summarizes all of the sub atomic
particles in the atom
Chlorine
17 p+
18 n0
Isotopes
• An isotope is any two or more forms of an
element, each having the same number of
protons, but a different number of neutrons.
• Isotopes of the same element have the same
chemical and physical properties.
• Some isotopes are unstable, or radioactive,
which means that the nucleus has a
tendency to break apart and eject very high
energy particles into its surroundings.
• Atoms that have unstable nuclei are called
radioisotopes.
Ch. 4
A Family is also called a Group.
based on their atomic numbers.
Groups or
Families
•
•
•
•
Periods
• Each horizontal row of
Columns of elements are
elements is called a period.
called groups or families.
• The elements in a period are
not alike in properties.
Elements in each family have
• In fact, the properties
similar but not identical
change greatly across even
properties.
given row.
For example, lithium (Li),
sodium (Na), potassium (K), • The first element in a period
is always an extremely
and other members of family
active solid. The last
IA are all soft, white, shiny
element in a period, is
metals.
always an inactive gas.
All elements in a family have • The period tells us how
the same number of electrons many orbitals the element
has.
in their outer orbital.
Noble Gases
• Noble Gases are colorless gases that are extremely unreactive.
• One important property of the noble gases is their
inactivity. They are inactive because their outermost
energy level is full.
• Because they do not readily combine with other elements
to form compounds, the noble gases are called inert.
• The family of noble gases includes helium, neon, argon,
krypton, xenon, and radon.
• All the noble gases are found in small amounts in the
earth's atmosphere.
Alkali Metals
The alkali metals
(group 1A) are
located in the far left
column of the periodic
table.
• These metals are highly reactive and readily form
compounds with other elements. Most commonly H,
O, Cl, F, Br, I.
• The reactivity of alkali metals is explained by their
structure. These metals have only one electron in
their outer orbital. They will readily lose this
electron to become a stable atom.
•
•
•
•
Halogens
Group VII A
Include F, Cl, Br, I, At
Next to the noble gases
These are the most
reactive non metals. They
almost always appear
naturally as compounds
(Cl2, Br2 , etc.)
• They make very useful compounds such as iodized
table salt, chlorine in drinking water, sodium
fluoride in toothpaste, etc.
• The reactivity of halogens is explained by their
structure. These non metals need only 1 electron
to fill their outer orbital. They will readily gain
this electron to become a stable atom.
A Group of One
• Hydrogen is a unique element.
• It has only 1 electron. Therefore it has only
one orbital (How many electrons can this
orbital hold?)
• It can react as both a metal and a non metal.
It can either lose or gain 1 electron to
become a stable atom.
• Most of the Earth’s hydrogen exists in
compounds due to it’s high reactivity.