Transcript Document

Energy, Atoms and Molecules
 The
capacity to do work or
produce heat
 Measured in calories or Joules
 Law of Conservation of Energy:
E is neither created nor
destroyed
 Temperature is a way to
measure heat energy.
Energy
Celsius vs Kelvins
 Anything
with mass and
volume
 Physical changes = crushing,
tearing, state changes
 Chemical Changes = alter the
chemical identity of the
substance
Matter

Matter is neither created nor
destroyed
Law of Conservation of
Matter
A
substance that cannot be
separated into simpler
substances by chemical
change.
 Elements are composed of
atoms.
Elements
Making the Periodic Table of
Elements via Stellar Evolution
 Helium Fusion in Stars
 Creating Carbon and Beyond
 Up to Iron
 The Relative Abundances of the
elements reflect these fusion
reactions. Elements divisible by 4
are the most abundant.
Where did elements come from?
 Learn
the first 54 element
symbols !
Hydrogen (#1) = H
Helium = He
Lithium = Li
Beryllium = Be
To (#54) Xenon = Xe
What Symbols?
Nemonics and tools:
Au, give me your gold!
Cu in the copper mine!
Did you hear about the date between
oxygen and potassium? (it was OK)!
Did you hear about the date between
oxygen and magnesium?
(it was OMG)!
 Two
or more atoms
bonded together.
Compounds
 Heterogeneous-
visibly different
parts of a mixture
 Homogeneous- looks the same
throughout
Mixtures

Atoms are unbelievably tiny. How
tiny? Incredibly smaller than plant
and animal cells. Billions of atoms
make up the writing tip of your pen
or pencil.
Atomic Size
Atom Characteristics
 All
matter is made of atoms.
 Space (without any particles)
has no atoms.
 Atoms are made of smaller
particles protons +
 neutrons ( ) and electrons (-)
 Protons, neutrons, and
electrons, of course, are made
of even smaller particles…
 Protons,
electrons and
neutrons are made of even
smaller particles including,
Quarks, bosons, fermions, mesons, etc.
Particle physics studies these entities
(you don’t need to know these in Chem 1 &2).
Sub-subatomic
particles
 Positvely
charged
 Equals the atomic number of
an atom.
 Always stays the same for an
element.
 Located in the nucleus of the
atom.
Protons
 Neutral charge
 Number of neutrons
= Atomic
mass minus the atomic number.
 Different isotopes have
different numbers of neutrons.
 Always reside in the nucleus.
(a neutron walked into a bar)
Neutrons
 Negative electrical charge
 Electrons equal protons in
atoms.
 Missing electrons make positive
ions.
 Extra electrons make negative
ions.
 Located in shells outside
nucleus.
Electrons
Hot or
Not?
The End of Part 1
Definitely HOT!
ISOTOPES
Many elements have different types of
atoms, each with different numbers of
neutrons. Each type is called an
isotope. Hydrogen has 3 isotopes: H-1,
H-2 and H-3.
Isotopes with higher numbers of
neutrons than normal tend to be
radioactive. For example, H-3 or
tritium isotopes tend to
spontaneously give off electrons
called beta particles. This is
called radioactive decay.
How do they do this?
Isotopes
Radioactivity
 Most
elements have isotopes that give
off neutrons or protons or electrons
spontaneously into space at high
speeds.
 Alpha Particle = 2 protons and 2
neutrons
 Beta Particle = electron
 Gamma Ray = electromagnetic wave.
 All three types of radiation are
ionizing (dislodge electrons and cause
chemical reactions to happen)
Radiation Types
Penetrating
Power
paper stops alpha
aluminum foil stops beta
thick lead or concrete stops gamma
Natural Radioactive
Decay

http://www.visionlearning.com/library/mo
dule_viewer.php?mid=59

http://www.furryelephant.com/player.php
?subject=physics&jumpTo=re/2Ms4
Nuclear Chemistry Review Links
 The
average atomic mass
(protons and neutrons) is the
weighted average of the
different isotopes.
weighted mass =
% abundance X mass
Finding Average Atomic Mass
% abundance X mass = weighted mass
Cl-35 75.53 x 34.97 = 26.41
Cl-37
24.47 x 36.97 = 9.04
Average atomic mass = 35.45
Ions
 Sodium
has 11 protons and 11
electrons. When it loses an
electron, it becomes a cation with a
+1 charge, Na+1
Chlorine has 17 protons and 17
electrons. When it steals sodium’s
electron, it will have 18 electrons,
and becomes an anion with a –1
charge. Cl-1
+cations and - anions
Ion Examples
 Positive
and negative
ions are attracted to each
other and form ionic bods
to make a compound.
Na+1
 Sodium
Cl-1
and chlorine bond to
each other to become a formula
unit of sodium chloride.
Hot
or
Not?
Atoms and Compounds:
Definitely HOT!
The End