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Classification of Matter
Jared Heidinger M.D. Ph.D.
Classification of Matter
matter – anything that has
mass and takes up space, can
be in mixture or pure
substance
• Atom – smallest particle of an
element still characteristic of
that element
• compounds – distinct particles
composed of two or more
atoms
Classification...
• heterogeneous substance
(mixture) – may consist of
more than one phase, nonuniform (glass of water with ice
in it)
• homogeneous substance
(mixture) – uniform and
consist of only one phase
Classification...
• pure substance –
homogeneous matter with a
defined set of physical and
chemical properties, cannot be
separated by physical changes,
can be with electricity and heat
(elements and compounds)
• element – composed of only
one kind of atom, Au, Na, Cu
(can’t be broken down by heat
or chem rxn)
• compound – substance can be
decomposed chemically by heat
or electricity – substance
composed of two or more kinds
of atoms (water, salt)
• chemical decomposition –
process to separate a
compound into its elements
• compounds at brainpop.com
• solutions – homogeneous
mixture of dissolved substances
containing at least one solute
and one solvent
• Figure 1.8, pg. 36 – Diagram
• Chemical formula – used to
represent elements and
compounds in their proper
proportions
• Standard Ambient
Temperature and Pressure
(SATP) – unless other
conditions are specified
descriptions of materials are
assumed to be at 25 deg. C,
and 100 kPa.
• Metals – usually shiny solids at
SATP, good conductors of heat,
electricity, bendable malleable,
ductile
• Non-metals – solids, liquids,
gases at SATP – poor
conductors, when in solid form
they are brittle, lack lustre of
metals
Periodic Table
• Periodic Law – when elements
are arranged in order of
increasing atomic mass,
chemical and physical
properties form patterns that
repeat at regular intervals
• Mendeleyev – created a periodic
table and left blanks in for
missing but predicted elements
• accurate predictions
Modern periodic table
• Family (group) – elements
with similar chemical properties,
vertical columns
• Period (row) – metallic to
non-metallic forms from left to
right on the table, rows
• Metals on left of the staircase,
non-metals on right of the
staircase
You will find, amongst a great
many things...
• Atomic mass – defined relative
to the mass of a carbon atom,
which is 12 mass units (one
atomic mass unit is 1/12th the
mass of a carbon atom
• atomic mass = protons plus
neutrons
Names of Groups or Series
of Elements
• Alkali metals (Group 1) – soft,
silver colored metals
• react violently with water to
form basic solutions
• cesium and francium are most
reactive
• Alkaline-earth metals (Group 2)
– light reactive metals
• form oxide coatings when
exposed to air
• these seal surfaces and
prevent further reaction
• Transition metals (Groups 3 –
12) – exhibit a wide range of
chemical and physical
properties
• Halogens (Group 17) –
extremely reactive
• fluorine is the most reactive
• Noble gases (Group 18) –
extremely low chemical
reactivity
• ASSIGN p.g. 55 - #1,4,5
and p.g. 67 #3
Chapter 2
Atomic Theories
• Theories – ideas based on
principles that explain a large
number of observations
• continually undergo change
Greek Theory of Matter
• Everything made from atoms
• small indivisible particles
(atomos – greek for
uncuttable)
• could be different sizes
• had geometric shape
• were in constant motion
Dalton’s Atomic
Theory (Billiard Ball)
• All matter is composed of
tiny, indivisible particles
called atoms
• Atoms of an element have
identical properties
• Atoms of different elements
have different properties
• Atoms of two or more
elements can combine in
constant ratios to form new
substances
J.J. Thomson (fruit cake,
raisin bread, you get the
drift)
• atom had negatively charged
particles – electrons (subatomic particles with a negative
charge, small mass)
• Nagaoka – electrons around a
positive center like the planet
Saturn
Rutherford
• shot alpha particles (positively
charged particles) at thin gold foil.
• bounced back, deflected at large
angles, had to be a postitively
charge body in the center of the
atom
Rutherford’s experiment
• link
• Proton - subatomic particle
having a single positive electric
charge (1840X the mass of an
electron)
Mosely
• atomic number – number of
protons in the atom (number on
the periodic table)
• James Chadwick – neutrons –
particles with no charge that
contain most of the mass of the
atom (glue together the
protons, mass slightly greater
than proton)
Frederick Soddy
• isotope – form of an element
with a different number of
neutrons
Eg- carbon has 6 protons and 6
neutrons (also called carbon 12
{6 neutrons + 6 protons}) an
isotope of carbon is carbon 14,
which has 8 neutrons
• carbon 14 is radioactive but has
similar chemical properties of
carbon 12
• mass number – the sum of
the number of protons and
neutrons in an atom
• radiation
• Fig. 2.19, pg. 59
• atoms at brainpop.com
Assignment
• Collecting information using the Periodic
Table Worksheet
Bohr’s Atomic Theory
• fixed quantity of
energy/electron related to the
circular orbit in which the
electron is found
• cannot exist between orbits,
can move to unfilled orbits if
energy is absorbed or released
• Higher energy = further
distance from nucleus
• max. #of electrons in 1st three
energy levels is 2, 8, and 8
• atom with a max. number of
electrons in its outermost
energy level (valence electrons)
is stable (unreactive)
• Fig. 2.22 – pg. 61
• first 3 levels, the max number
of electrons is 2, 8, and 8
respectively.
• Ground state – electrons in
lowest possible energy levels
(no excess energy is being
applied to the atom)
Quantum Mechanics
• protons occur in the nucleus
(atomic# = # of protons)
• electrons in energy levels (less
energy, closer to the nucleus),
# electrons=# protons in
neutral atom
• # energy levels usually= the
period (row) number
• www.fearofphysics.com
• Valence electrons– electrons in
the highest energy level (some
elements the # valence
electrons = the last digit of the
group number for that atom,
e.g. nitrogen)
• Explain electron level
diagrams
Assignment
• ASSIGN pg. 64 - #12, pg. 68
- #5,6,8,11,13,15
• “Atomic Structure”
Worksheet - Atoms Side
Only
Formation of Monoatomic ions
• When neutral atoms collide, an
electron is transferred from one
atom to the other
• Ions – particles that have an
electrical charge due to a
transfer of electrons
• Monoatomic ions – single
atoms that have lost or gained
electrons
• high reactivity because of
unfilled or overfilled electron
levels
• Cations - positively charged
ions(all are metals, formed
when they lose an electron(pair
of socks))
• Anions – negatively charge
ions (all are non-metals, formed
when they gain an electron)
• ASSiGN \- pg. 68 - #’s 14, 17, 18
• Assignment 10-2