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 are the most abundant. of the elements reflect these fusion reactions. Elements divisible by 4 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
P ositvely 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
N egative electrical charge Electrons equal protons in atoms.
Missing electrons make positive ions.
Extra electrons make negative ions.
Located in shells outside nucleus.
Electrons
Hot Not ?
or
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 Cl -1 Sodium and chlorine bond to each other to become a formula unit of sodium chloride.
Hot Not ?
or Atoms and Compounds:
Definitely
HOT