Transcript Unit 2 Review: Chemistry - Mr. Hoover's Science Classes

UNIT 2 REVIEW: CHEMISTRY
MATTER THAT HAS CHEMICAL
AND PHYSICAL PROPERTIES
KEY CONCEPTS
•
Particle theory of matter
 • States of matter
 • Classifying matter
 • Observing physical properties
 • Observing chemical properties
 • Usefulness and impact of substances’
properties
MATTER HAS MANY FORMS
Matter – anything that has mass and
volume.
 Mass is a measure of the quantity of an object. (g,
kg,)
 Volume is a measure of space taken up (mL,
L)


Matter can be found as a solid, liquid or gas. (or
even a combination of these)
CHANGES OF STATE

There are 3 states of matter
Solid
 Liquid
 gas

TERMS FOR CHANGES OF STATE
THE PARTICLE THEORY OF MATTER (4
POINTS)

1.
2.
Way of describing matter.
All matter is composed of very tiny objects
called particles.
Each Pure substance has its own kind of
particles, different from the particles of
other pure substances.
THE PARTICLE THEORY OF MATTER (4
POINTS)
3. Particles present in matter are always in
motion. They may be vibrating back and forth,
as in a solid, or moving in all directions, as in a
gas. In a liquid, particles stay close together but
can slide past one another.
4. The particles in a substance attract each
other. The amount of attraction is different for
different kinds of particles. All particles have
spaces between them.
THE PARTICLE THEORY OF MATTER (4
POINTS)

The distances between the particles change for
different states of matter.
CLASSIFICATION OF MATTER
Matter
Pure
Substances
Element
Compound
Mixture
Mechanical
Mixture
Suspension
Solution
PURE SUBSTANCES (2)
A pure substance is made up of only
one kind of matter
 unique set of properties

A
colour, hardness, boiling point, and
melting point.
pure substance is either an
element (gold) or a compound
(sugar).
ELEMENT
A pure substance that cannot be broken down into
any simpler substance by chemical means.
 Each element has its own name and symbol.
Example: Gold (Au)
COMPOUND
A pure substance that is made from two or more
elements that are combined together chemically.
 Example, water (H2O) is a compound containing
the elements hydrogen and oxygen.

MIXTURES (3)
A
mixture is a combination of pure
substances.
 Each substance remains in its original,
pure form, although each is not always
easy to see distinctly once the mixture is
made.
MECHANICAL MIXTURE
(HETEROGENEOUS MIXTURE)
 Different
substances that make up the
mixture are visible
 Hetero = different
SUSPENSION
A
cloudy mixture in which tiny particles of
one substance are held within another.
 Can be separated out when the mixture is
poured through filter paper.
 A suspension is also a heterogeneous
mixture.
SOLUTION (HOMOGENEOUS MIXTURE)
 Different
substances that make it up are
not individually visible
 One substance is dissolved in another
 The prefix “homo-” means same, and all
parts of a homogeneous mixture look the
same.
PHYSICAL PROPERTIES


-A physical property describes a
characteristic of a substance that can be
observed or measured without changing the
composition of matter.
Example: Melting Point, Boiling Point
OBSERVING PHYSICAL PROPERTIES
Property
Description
Examples
Colour and
lustre
The light the substance reflects
gives it colour and lustre
(shine)
The names for some
substances, such as gold,
are also the names of colours.
Gold has lustre; concrete is dull
Conductivity
Conductivity is the ability
of a substance to conduct
electricity or heat. A
substance that conducts
electricity or heat is called a
conductor. A substance with
little or no conductivity is an
insulator.
Most metals are good
conductors. Copper is a very
good conductor of electricity and
so is used to make electric wires.
Styrofoam® and glass are
insulators.
What it looks like
OBSERVING PHYSICAL PROPERTIES
Property
Description
Examples
Density
Density is the amount of
mass in a given volume
of
a substance.
D = m/v
Ductility
Any solid that can be
stretched into a long
wire is said to be
ductile.
The density of pure water
is 1 g/mL.
The density of gold is 19
g/mL.
Water is denser than oil,
but gold is denser than
water.
Copper is a common
example of a ductile
material.
What it looks like
OBSERVING PHYSICAL PROPERTIES
Property
Hardness
Malleability
Description
Hardness is a substance’s
ability to resist being
scratched. Hardness is
usually measured on the
Mohs hardness scale from
1 to 10.
A substance that can be
pounded or rolled into
sheets is said to be
malleable.
Examples
The mineral talc is the
softest substance on the
Mohs hardness scale (1).
Emerald is quite hard (7.5).
Diamond is the hardest
(10).
Aluminum foil is an
example of a malleable
substance.
Metals such as gold and tin
are also malleable.
What it looks like
PHYSICAL CHANGE
In a physical change, the substance involved
remains the same (chemically). The substance
may change form or state, however. All changes
of state are physical changes.
 Examples: Dissolving a substance in a liquid,
breaking something.
 NOTE: Most physical changes can be reversed.

OBSERVING CHEMICAL PROPERTIES
A chemical property describes the ability of a
substance to change into a new substance or
substances.
 In order to view a chemical property a chemical
change must occur.



Chemical change - the formation of a new
substance or substances with new properties.
A chemical reaction is a process in which a
chemical change occurs.
CHEMICAL PROPERTIES
1. Combustibility is the ability of a substance to
burn. In order to burn a substance requires
Oxygen
CHEMICAL PROPERTIES

Light sensitivity is a chemical property of that
can cause new substances to form when light hits
it.
CHEMICAL PROPERTIES
3. Reacting with an acid is a chemical property
where when acid is poured on a substance it
produces a gas and bubbles.
CLUES THAT A CHEMICAL CHANGE HAS
OCCURRED
Clue
Evidence
Change in colour
Final product(s) may have a
different colour than the colours of
the starting material(s).
Formation of a
solid (precipitate)
Final materials may include a
substance in a state that differs from
the staring material(s): Precipitate
CLUES THAT A CHEMICAL CHANGE HAS
OCCURRED
Clue
Formation of a gas
Evidence
Final materials may include a substance
in a state that differs from the staring
material(s); commonly, a gas
Release / absorption Energy (light, electricity, sound or most
of heat or light
commonly heat) is given off or absorbed.
The change is difficult The change cannot be reversed or it is
to reverse
difficult to.
SUMMARY
• All matter is composed of moving particles that
attract one another but have spaces between
them.
 • Matter can be solid, liquid, or gas, or a
combination of states and can change from one
state to another.
 • Elements and compounds are pure substances.
Mechanical mixtures, suspensions, and solutions
are combinations of pure substances.

SUMMARY
• Physical properties are characteristics of a
substance that can be observed or measured
without changing what the substance is. Physical
properties include boiling point, colour,
conductivity, viscosity, and adhesion, cohesion,
and other special properties of water that are
important in living systems.
 • Chemical properties describe how substances
react with other substances or to light or heat
and can be observed when chemical changes
occur.

KEY TERMS

Read each one and then try to define it, if you do
not know the meaning of it look it up in your
notes and write it down.
THE PERIODIC TABLE ORGANIZES
ELEMENTS BY PATTERNS IN
PROPERTIES AND ATOMIC
STRUCTURE
KEY CONCEPTS
•
Atomic theory
 • Atomic models
 • Subatomic particles
 • Element names and symbols
 • Properties of common elements
 • Periodic table
 • Properties of chemical groups
Evolving Models of the Atom
 Atomic theory is the study of the nature of
atoms and how they combine to form all
types of matter. Atomic theory helps us to
understand why there are different kinds of
atoms. It explains how atoms combine to
form over 100 known elements and all other
forms of matter, including compounds and
mixtures.
John Dalton (1766–1844),
 a scientist and teacher in England,
reconsidered the ancient idea that each
different kind of element is composed of a
different kind of atom. Dalton thought that
the atom would be like a featureless
sphere.
John Dalton (1766–1844),
He used the following theory to explain the
nature of matter:
 All matter is made of small, indivisible
particles called atoms.
 All the atoms of an element are identical in
properties such as size and mass.
John Dalton (1766–1844),
 Atoms of different elements have different
properties.
 Atoms of different elements can combine in
specific ways to form new substances.
 Atoms cannot be created, destroyed, or
subdivided in a chemical change.
J. J. Thomson (1856–1940),
 He found that the atom is not the smallest
particle. There were particles within the
atom.
 He theorized that an atom was a positively
charged sphere with negative charges
embedded in it.
J. J. Thomson (1856–1940),
 In 1897 he proposed a
revolutionary new
model for atoms. It is
known as the raisin bun
model. The dough
would be the positively
charged sphere and the
raisins would be the
negative charges.
It is also known as the
plum pudding model
Ernest Rutherford (1891–
1937)
 Rutherford had discovered the nucleus, the
centre of the atom.
 This tiny positively charged part of the atom also
contains most of the atom’s mass.
Atoms are composed of three
subatomic particles
1. Protons- Heavy positively charged found in the
nucleus
2. Neutrons -are neutral particles that have the
same mass as protons and are located in the
nucleus
3. Electrons- Negatively charged particles with
almost no mass. They circle the nucleus at
different energy levels.
Atoms are composed of three
subatomic particles
 Atoms are electronically neutral so the number
of electrons = the number of protons
Niels Bohr (1885–1962),
Name
Proton
Symbol Relative Electric Location
Mass
Charge
p
1836
1+
Nucleus
Neutron
n
1836
0
Nucleus
Electron
e
1
1-
In energy
levels
surround
nucleus
The Elements
 Elements are pure substances that consist
of atoms.
 The periodic table consists of over 100
elements all of which have a certain spot on
the table.
Non-Metals
 Found on the Right side of the periodic
table
 Most of the remaining elements in the
periodic table are non-metals (17 of them).
Non-Metals
Non-metals generally have these properties:
 Non-conductor of electricity in its solid form
 At room temperature most are gasses (11) or
solids (5) and only one is liquid.
 Solids are brittle and lack the lustre of metals
Metalloids
 Found in the middle-right of the periodic
table
 Some elements do not fit as metals or nonmetals. These fit on either side of the
staircase that divides the metals and the nonmetals.
 They have some properties of metals and
some properties of non-metals. They are
called semiconductors because they do not
conduct electricity well.
Metalloids
 It is easier to control the flow of electricity
through semiconductors than it is
conductors, which explains their wide use in
electronics.
METALLOIDS

Silicon is the most common metalloid, in its pure
form it is shiny, grey and very brittle. Around
40% of all rock is silicon.
THE MODERN PERIODIC TABLE
A
TOMIC NUMBER (Z)
 Atomic number - the number of
protons in an atom of an element.


Each element has a set number of
protons and every atom from that
element will have that many protons.
The pattern for increasing protons moves
from left to right and then down to the
next row just like reading a book.
ATOMIC MASS (A)




Atomic mass - the average mass of an element’s
atoms.
Atomic mass is given in atomic mass units (amu).
H has a mass of 1.01 amu. This means that iron
atoms are about 55.85 times heavier than hydrogen
atoms.
Atomic masses are always expressed as decimal
fractions. One reason that they do not have whole
number values is that, except for fluorine, atoms of
the same element have different numbers of neutrons.
ATOMIC MASS (A)

Example: A hydrogen atom has one
proton and one electron but no
neutron. A small percentage of
hydrogen atoms have 1 p, 1e, and
1n. 1 p, 1e, and 2n.
 Atomic
mass generally increases
in order of atomic number.
 Exception: iodine (I) has a lower
atomic mass than tellurium (Te).
ION CHARGE


Elements with atoms that can form
similar ions are grouped together in the
periodic table. Metals generally lose
electrons and become positive ions.
Many non-metals can gain electrons
and so become negative ions.
CALCULATIONS
Determining the number of protons
 Look at the atomic number given on the
periodic table (atomic number)

Example: H = 1, He = 2, Li = 3
CALCULATIONS
Determining the number of neutrons
 Subtract the atomic number (# of protons)
from the Atomic mass (# of protons and
neutrons)


Atomic mass – atomic number (A – Z = N)
Example: Iron
 55.85 – 26 = 30 neutrons
CALCULATIONS
Determining the charge of Ions
 Subtract the number of electrons from the
number of protons
Protons (P) – Electrons(E) = Ion Charge
 Example: Iron
2+
 26 – 24 = 2+ charge = Fe
 26 – 23 = 3+ charge = Fe3+
 Example: Fluorine

9
– 10 = 1 – Charge = F-
Bohr Diagrams
 To represent electron arrangements at
various orbits we use Bohr diagrams. Each
orbit has a set number of electrons.
Orbit #
1
2
3
4
# of Electrons
2
8
8
18
 Every row in the period contains a shell. The
farther you move down the table the more
shells you added to the diagram. H = 1 shell,
Li = 2 shells, K = 3 shells.
 Moving left to right on the periodic table adds
valence electrons to the shells of that row. Na
has 1 valence e-, Mg has 2 valence e-, Al has 3
valence e-, etc.
Metals
 Tend to have 1, 2, or 3 electrons in the outer
orbits (shells)
 They lose electrons when they combine with
other elements to form positive ions (cations)
: note the t in the word think +
 They lose electrons, thus they have the same
electron arrangement as the Noble gas a row
above them
Metal Ion
Example
 Sodium: Na  Na+
N 12
N 12
P 11
P 11
Non-Metals
 Non-metals – Tend to have 4, 5, 6, or 7
electrons in their outer orbits (shells).
 They gain electrons to form negative ions
(anions)
 They gain electrons, thus they have the same
electron arrangement as the Noble gas in the
same row.
 Example
 Fluorine : F  F-
N 10
N 10
P 10
P 10
SUMMARY
•
Every element is composed of a distinct
type of atom.
 • The atomic model continues to be
revised based on new experimental
evidence. Bohr diagrams are one way to
represent atomic structure.
 • An atom has a dense nucleus of
neutrons and protons, which is
surrounded by shells of electrons.
SUMMARY
•
Each element has a standard name and
symbol.
 • The periodic table organizes the metals,
non-metals, and metalloids based on
properties such as number of protons in
an atom.
 • The alkali metals share similar
properties, such as conductivity, which
are different from the properties of the
halogens and noble gases.
KEY TERMS

Read each one and then try to define it, if you do
not know the meaning of it look it up in your
notes and write it down.
ELEMENTS COMBINE TO FORM
IONIC COMPOUNDS AND
MOLECULAR COMPOUNDS
KEY CONCEPTS
•
Compounds
 • Chemical bonds
 • Chemical names and formulas
 • Using elements and compounds
Ionic Compounds
 Ionic compounds are formed by combining
metals with non-metals in fixed proportions.
An ionic compound is formed when one or
more valence electrons are transferred from a
metal atom to a non-metal atom.
Ionic Compounds
 This leaves the metal ion as a cation and the
non-metal ion as a anion. The two oppositely
charged ions are attracted to each other by a
force called a ionic bond.
 The smallest amount of substance that has
the composition given by its chemical
formula is the formula
Ionic Compounds
 Sodium chloride
 NaCl is a 1:1 ratio
Ionic Compounds
 Magnesium chloride
 MgCl2 is a 1:2 ratio.
Ionic properties
 Ionic compounds are solids at SATP. In their
solid form they form solid ionic crystals.
These are more commonly known as salts
The Cross over rule
Step 1.
 Write the symbols, with the metal first (the
element with the positive charge)

Mg
I
The Cross over rule
Step 2
 Write the Ionic charge above each symbol to
indicate the stable ion that each element
2+
Mg
I
The Cross over rule
Step 3
 Draw an arrow from the metals charge to the
non-metal and an arrow from the non-metal
charge to the metal. (Cross over the arrows)
2+
Mg
I
The Cross over rule
Step 4
 Fill in the number of atoms from each
element will have by following the arrows.
 If need be reduce to lowest terms (in other
words, if they are the same number, you
don’t write those numbers down because you
could divide the whole molecule by that
number which would = 1)
 MgI2
(if the number crossed is a 1, the 1 is
not shown)
Molecular Compounds
 When non-metals combine, a pure substance
called a molecular compound is formed. In
molecular compounds, the atoms share
electrons to form covalent bonds. The atoms
bonded together are called molecules.
 Nomenclature - a branch of taxonomy
concerned with the application of scientific
names to taxa, based on a particular
classification scheme and in accordance with
agreed international rules and conventions
Ionic Compounds: IUPAC
Naming
Metal non-metal -ide
 Consists of two types of monoatomic ions
(elements with only one possible ion charge)
1. The metal ion is always written first and
retains its whole name
2. The non-metal is written second and has a
slight change, the ending (suffix) is changed
to –ide
Ionic Compounds: IUPAC
Naming
 Do not write ones (Ex Na1Cl1) and if both
elements have the same number reduce to
lowest terms (Ca2O2 = CaO)
Example:
 Na+ Cl- use the cross over method NaCl
 IUPAC name: sodium chloride
 The metal name is written in full and the non-
metal has the –ide suffix added to it.

Sodium chloride
 Binary compounds can be made up of more
than two ions, provided that there are only
two types of elements. Example: Al2O3
 STUDY TIP: All metals in group 1 and 2 follow
periodic law. Check all the others metals
when naming.
Example:
 MgS =
Magnesium sulphide
 Magnesium Phosphide =
Mg2+ P3Mg3P2
MOLECULAR COMPOUNDS
Ionic compounds can only bond to non metals in
so many ways.
Ex for every Ca we can only bond 2 F to it.
Molecular compounds do not work that way.
Molecular compounds can have various numbers
of atoms bonded together to create various
molecules.
 Ex. NO, NO2, N2O2, etc.

MOLECULAR COMPOUNDS

Due to this method of bonding there are
thousands more molecular compounds than there
are ionic compounds.
MOLECULAR COMPOUNDS
Most molecular compounds share the following
properties:
 can be solids, liquids, or gases at room
temperature
 usually good insulators but poor conductors of
electricity
 have relatively low boiling points
WAYS OF REPRESENTING MOLECULAR
COMPOUNDS
Bohr diagram ball and- stick Volume Filled
model
model
SUMMARY
are pure substances
composed of atoms of two or more
elements that are joined by chemical
bonds.
 • Ions with opposite charges attract
each other in ionic compounds, while
atoms in molecules share valence
electrons.

• Compounds
SUMMARY
•
The formulas for many common
compounds can be determined from
their names, and vice versa.
 • How we make use of electrons and
compounds affects society, the
economy, and the environment.
KEY TERMS

Read each one and then try to define it, if you do
not know the meaning of it look it up in your
notes and write it down.
QUESTIONS

Please do as many of the questions as possible.