The Nature of Matter
What is matter?
Matter: Anything that hass mass and volume
Matter can be measured in these ways:
• Volume: amount of space that matter takes up
• Mass: a measure of matter’s inertia (more mass = greater
inertia)
-mass is always constant, no matter where the object is in
the universe; weight is a measure of the force of gravity.
• Density: the mass of a given volume of a substance
• Length: You hopefully know what this is…
Physical properties of matter:
Physical Property: Things that
can be observed about a
substance or object without
changing the identity of the
substance or object.
Examples of Physical Properties:
• Color
• Odor
• Mass
• Volume
• How well it conducts
electricity
• Malleablity (ability to be bent
into shapes)
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Density ( d = m/v)
State at room temeperature
Heat or electricial conductivity
Ductility (ability to be pulled in
wire)
Characteristic property:
Characteristic property: a property of a
substance that can help identify a substance.
Examples:
• Copper has a reddish color
• Water has a density of 1 g/ml
• Diamonds are much harder than other
minerals.
Physical & Chemical Changes:
Physical Change: a change in a substance that
does not change the identity of a substance.
(example: crumpling up a piece of paper.)
Chemical change: a change in a substance that
changes its identity (examples: setting a piece of
paper on fire; iron rusting in salt water.)
Chemical Properties:
Chemical properties describe matter’s ability to
turn into other types of matter.
Examples:
• Flammability: the ability to burn (be converted
to energy)
• Reactivity: the ability to combine with other
types of matter and become a new substance
Signs of chemcial change:
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Change in color
Change in odor
Creation of gas (fizzing, bubbling)
Production of heat or other change in
temperature
• Creation of light
• Creation of sound (e.g., explosion)
The most important sign that a chemical change has
occurred is that it cannot be easily reversed.
Elements vs. Compounds:
Element: A substance which contains only identical
atoms.
Examples: hydrogen, helium, oxygen
Molecule: A group of atoms that are connected
(either by sharing or transferring electrons)
Compound: A substance that contains two or more
types of atoms that are chemically bonded togther.
Examples: water, carbon dioxide
How to Read the Periodic Table:
Checkpoint Quiz on Structure of the
Atom:
1. Describe the particle model of matter.
2. Draw and label a diagram of Thomson’s model
of the atom.
3. Who proved that an atom’s volume is mostly
composed of nothing at all?
4. An atom of nitrogen has an atomic number of 7
and an atomic mass of about 14. Draw a Bohr
diagram of an atom of this element.
5. Which part of an atom has a positive electrical
charge?
Isotopes of Atoms:
Isotope: the number of neutrons varies from the
most-common variety listed in the periodic table.
Example: Most atoms of carbon have 6 neutrons.
However, some carbon atoms may have more or
less than this number. Therefore, their mass may be
more or less than the usual 12 AMU (atomic mass
units)
Naming Isotopes:
Isotopes of a given
element are named
(numbered) according to
their mass number.
Example: a carbon atom
that has 6 protons and 8
neutrons has a mass of 14,
so the name of that
isotope is C-14 .
Properties of isotopes:
• Generally, isotopes of an element have the
same physical and chemical properties of
other isotopes of the same element.
• However, some isotopes have unstable nucleii,
and they decay rapidly (i.e, are radioactive.)
For example C-14 is somewhat radioactive
Forces Within atoms (and throughout
the universe):
• Gravity: exists because mass curves space-time
• Electromagnetic force: the force created by
particles with positive or negative electric charges
• Strong nuclear force: the force that keeps
particles in the atom from flying apart from one
another
• Weak nuclear force: The force that that allows
subatomic particles to turn into other types of
particles (and is the cause of radioactive decay)
Organization of the Periodic Table:
Elements, when arranged by atomic number (or
even by atomic mass), follow a pattern known as
the Periodic Law:
The physical and chemical properties of the
elements re-occur in a regular pattern as you go
through the elements in order of their atomic
numbers.
Groups and Periods:
The periodic table is
organized into groups and
periods:
Groups (columns) have
similar properties.
Periods (rows) have
similar atomic numbers
and masses.
Main Regions of the Periodic Table:
1. Metals: Most elements are
metals. They are mainly
listed to the left of the zigzag line (commonly called
the staircase). Most metals
are:
• Solid at 20 o C
• Shiny
• Ductile
• Malleable
• Good conductors of heat
and electricity
2. Nonmetals: Nonmetals
are mostly to the right of
the staircase. Most
nonmetals:
• Are gases or solids at 20o
C
• Have almost completely
full outer electron orbits
• Are poor conductors
• Are brittle (if solid)
3. Metalloids: metalloids
are found on the staircase.
They have some
properties of metals, and
some properties of nonmetals.
A More Detailed Look at the Table:
Properties of the Groups:
Group 1: Alkali Metals: They are highly reactive,
soft, and brittle. They all have one electron in their
outer orbit.
Group 2: Alkaline Earth Metals: They are like group
1, but slightly less reactive. They have 2 electrons in
their outer orbit.
Groups 3-12: Transition Metals: Have “normal”
properties of metals. They are less reactive than
groups 1-2. Electrons flow freely among atoms
(which is why they’re good conductors)
Group 17: Halogens. Very reactive nonmetals.
They frequently form chemical bonds with
metals in groups 1 and 2.
Group 18: Noble Gases. These gases have
completely full outer electron orbits, so do not
form bonds with any other elements. They are
always found in pure form in nature.
Homework:
LO: Describe the
organization of the
periodic table of the
elements.
SLE: Read and write
proficiently.
1. Read p. 114-120.
2. Answer the review
questions on p. 121
(on loose leaf).
States of matter and the particle
model:
Three states of matter:
1. Solids: have a definite
shape and volume.
Particles within solids are
vibrating, but not moving
much in relation to each
other.
Types of solids:
• Crystalline: particle
arrangement is very orderly,
and follows a definite
pattern.
• Amorphous: particle
arrangement is random
2. Liquids: liquids have a
definite volume, but they
take the shape of the
container they are in.
Particles in a solid move
around quite a bit, but
their energy level (and
velocity) is relatively low.
3. Gases: Gases have no
definite shape or volume.
The particles have a lot of
energy and are moving
very fast, and will rapidly
spread out to fill whatever
space they are in. The
space between gas
molecules is very large
compared to solids and
liquids.
Two Gas Laws:
1. Charles’ Law: Given the
same amount of pressure,
if you increase the
temperature of a gas, the
volume will also increase.
Boyle’s Law: Given the
same temperature, if you
increase the pressure on a
gas, the volume will
decrease.
Homework:
LO: Describe states of matter in terms of the
particle model of matter.
SLE: Read and write proficiently.
1. Read p. 36-45
2. Review questions p. 39, 45
LO: Describe endothermic and exothermic reactions.
SLE: Work cooperatively.
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Exothermic Reaction:
Endothermic Reaction:
1. Place thermometer in jar and close lid.
2. Wait 5 minutes and record
temperature.
3. Soak steel wool in vinegar for 5
minutes.
4. Wrap vinegar-soaked steel wool
around thermometer bulb, place back in
jar.
5. After 5 more minutes, record
temperature again.
1. Pour some vinegar (citric acid) into a
beaker.
2. Record temperature.
3. Stir in some baking soda.
4. Wait 30-60 seconds
5. Record temperature again.
Temperature before vinegar:
____________C
Temperature after Sodium bicarbonate:
_____________C
Temperature after vinegar: __________C
What happened? Why?
What happened? Why?
In general, what is the difference between
exothermic and endothermic reactions?
Temperature before Sodium bicarbonate:
___________C
LO: Describe the crystal structure of some solids
SLE: Work cooperatively
Salt crystal shape:
Sugar crystal shape:
LO: Describe states of matter
SLE: Apply academic habits for success
Checkpoint quiz on states of matter:
1. Describe the motion of particles in solids,
liquids and gases. (2 pts)
2. State Charles’ Law.
3. State Boyle’s Law.
4. If you decrease the pressure applied to a
certain volume of gas, what will happen to
the volume? Why?
Compounds and Chemical Bonds:
Review:
An element is a substance that
contains only a single type of
atom.
A compound is a substance that
contains molecules that are
composed of two or more
different kinds of atoms.
A molecule is a collection of two
or more atoms that are bonded
together through the transfer or
sharing of electrons.
Types of chemcial (molecular) bonds:
1. Ionic Bond: created when
an electron in the outer
orbit of one atom gets
transferred to another
atom. This transfer creates
two ions (atoms with
positive or negative charge)
, one of which is positively
charged, and one of which is
negatively charged. They
they bond together via
electromagnetic attraction.
2. Covalent Bonds: are
formed when two or more
atoms share electrons in
their outer (valence) orbit.
Diatomic molecules (O2
for example) are formed
by covalent bonds.
Homework:
LO: Describe kinds of chemical bonds
SLE: Work independently
1. Read p. 8-17 in Interactions of Matter
2. Review questions on p. 11 & 17
LO: Compare strength of covalent and ionic bonds.
SLE: Work collaboratively
Problem: Are ionic bonds harder to
break apart that covalent bonds?
Hypothesis:
Independent variable:
Dependent variable:
3 Controls:
Procedure:
1. Put salt (ionic bond, NaCl) in a
pan
2. Place pan on a hot plate and
heat on high for 5-10 minutes.
3. Repeat steps #1-2 with sugar
(Covalent bond, C6H12O6).
4. Observe and record results .
Observations:
What happened when salt was
heated:
What happened when sugar was
heated:
Conclusion:
LO: Describe how elements are chemically combined
SLE: Meet or exceed NGSS
Checkpoint Quiz on Chemical Bonds:
1. Describe how covalent bonds happen.
2. Describe how ionic bonds happen.
3. What part of an atom determines how it bonds
to other atoms?
4. Na (group 1) is most likely to form an ionic bond
with which group of atoms on the periodic
table? (Give the group number)
5. How many atoms (total) are in a molecule of
C6H12O6?
Law of Conservation of Mass:
In any physical system,
even during a chemical
reaction, the total amount
of mass (i.e., the total
number of atoms) will not
change.
LO: Model the law of conservation of mass.
SLE: Work collaboratively.
Problem: If a gas is produced in a closed
system during a chemical reaction, does the
total mass of the system stay the same?
Hypothesis:
Procedure:
1.
Pour some water into a ziplock bag and
seal it closed.
2.
Measure the total mass of the ziplock
bag and one tablet of Alka Seltzer.
3.
Open the ziplock bag, put one Alka
Seltzer tablet in the bag and quickly
reseal it.
4.
After 5 minutes, find the mass of the
bag again.
5.
Repeat Steps 1-4, but this time, instead
of re-sealing the ziplock bag after
adding Alka Seltzer, leave the bag open.
Data:
Type of
system:
Mass before
reaction (g):
Closed
Open
Conclusion:
Mass after
reaction (g):
Forming New Sustances:
Chemical Reaction: A
process in which one or
more substances is
changed into one or more
new substances with
different properties.
Reactants: the substances
you start out with.
Products: the substances
you end up with.
Signs of chemical reactions:
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Formation of a gas.
Formation of a new solid (precipitate)
Change in temperature
Change of color
Creation of light
Chemical Formulas:
Chemical formula: a formula that tells you what
molecules of a compound look like:
HCl: Hydrogen chloride; 1 atom of hydrogen, 1
atom of chlorine in each molecule.
H2SO4: Hydrogen sulfate; 2 atoms of hydrogen, 1
atom of sulfur, and 4 atoms of oxygen.
Predicting chemical formulas:
The formula for covalent compounds is just
based on the name:
Carbon disulfide: 1 C, 2S, so it’s CS2
Carbon monoxide: 1 C, 1O, so it’s CO
For ionic compounds, you have to know the
group numbers and charges of the ions:
Magnesium Chloride: Mg is in group 2 and has a
charge of -2; Cl is in group 17, has room for 1
extra electron, so has a charge of +1: But Mg
want to give 2 electrons away, so 2 Cl atoms are
involved in the bond: MgCl2
Charges of polyatomic ions:
• Ammonium ion, NH4;
1+
• Carbonate ion, CO3; 2−
• Hydroxide ion, OH; 1−
• Nitrate ion, NO3; 1−
• Phosphate ion, PO4; 3−
• Sulfate ion, SO4; 2−
Unfortunately, because
polyatomic ions involve
reactions with molecules
that are based on covalent
bonds, these need to just
be remembered or looked
up.
Chemical Equations:
Chemical Equation: a way to describe what
happens in a chemical reaction by displaying the
changed chemical formulas of the substances
involved.
Reactant  Product
Balancing Chemical Equations:
It’s really important that chemical equations:
1. Reflect reality;
2. Reflect (obey) the law of conservation of
mass.
C + O2  CO2
To balance equations, because of the way
electrons move around in chemical bonds,
coefficients must be added to the equation:
H2 + O2  H2O : Not balanced
2H2 + O2  2H2O Balanced
Homework:
LO: Describe chemical reactions using chemical
equations.
SLE: Work independently.
1. Read pages 28-37 in Interactons of Matter.
2. Complete review questions on p. 37 (on
loose leaf).