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Mass
• Quantity of matter an object has• NOT weight: the amount of force produced by
gravity acting on mass
Elements
• Substances that cannot be broken down chemically into simpler kinds of matter
• More than 100 types• Organized on the
periodic table of elements
Elements of Life
• Approximately 27 are essential to life• 90% of mass of living things are O, C, H, N• Elements of Life: CHONPS• Remember the Elephants in the Element
Song?
Nucleus
• Central region of an atom• Contains the bulk of the mass of the atom• Consists of protons and neutrons
Proton
• Positively charged particle• Located in Nucleus• Mass approximately 1 AMU
http://www.fas.org/nuke/guide/usa/doctrine/dod/fm8-9/fig2-I.gifhttp://images.thecarconnection.com/med/proton-logo_100378711_m.jpg
Neutron
• Neutral charged particle, No Charge• Located in Nucleus• Mass approximately 1 AMU
http://www.chem4kids.com/files/art/atom_struct1.gif
http://d1jqu7g1y74ds1.cloudfront.net/wp-content/uploads/2010/02/c-atom_e1.gif
http://www.chem4kids.com/files/art/atom_neutron1.gif
Electron
• Negatively charged particle• Orbits the nucleus in the electron cloud• Mass practically zero
Orbitals
• Electrons orbit in specific regions called orbitals-
• 3D space higher probability location of orbital• Each orbital is associated with an energy level• Electrons in orbitals further from the nucleus
have more energy
Electron Orbitals & Energy Levels
• Each orbital can hold 2 electrons• Each energy level consists of different #s of
orbitals
http://quantumnumbers.weebly.com/uploads/1/2/2/1/12213482/8009912_orig.jpeg
Atomic Number
• Number of protons in an atom • Determines type of element• Elements are organized by atomic number on
the periodic table• Atomic Number for Carbon is 6
Mass Number
• Total number of Protons + Neutrons
• Protons have mass of 1 amu
• Neutrons have mass of 1 amu
• Mass Number – Atomic Number = # of neutrons
http://www.sawyerscience.com/assets/images/units/unit_2/atomic_Mass.jpg
Mass Number
http://chemwiki.ucdavis.edu/@api/deki/files/8320/He_Atom.png
http://1.bp.blogspot.com/-DFx20P3q3fw/TciZDNxjLQI/AAAAAAAAACU/BsGwZgYExOM/s1600/isotopes.jpg
Isotopes
• Atoms are stable with certain numbers of neutrons
• Atoms with different numbers of neutrons are called Isotopes
Compounds
• Made of atoms of two or more elements in fixed proportions
• Chemical formula shows kinds and proportions of atoms
• H2O -
• C6H12O6 –
• CO2- • CO - • O2- Compound?
Molecule
• Simplest part of a substance that retains all properties of that substance
• Can exist in a free state• Can be very large- carbohydrates, lipids, proteins, nucleic
acids (macromolecules)• H2O -
• C6H12O6 –
• CO2- • CO - • O2-
Chemical Bonds
• Attractive forces that hold atoms together• Covalent Bonds• Ionic Bonds• Hydrogen Bonds
Stable Atom = Highest energy level filled
Valence Electrons
• Number of electrons in the highest energy level for that atom
• Atoms are more stable when outer energy level is full (2 or 8 electrons depending on element)
Dot Diagrams
• Show the valence electrons on an atom• Hydrogen and helium only hold up to 2
valence electrons• Other elements (that we will look at) hold up
to 8 valence electrons
http://webgenchem.com/lewishcn.gifhttp://legacy.jyi.org/volumes/volume3/issue1/features/peterson.html
Covalent Bond
• Two atoms share one or more pairs of electrons
http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20101/bio%20101%20lectures/chemistry/chemistr.htm
Ion
• Some atoms only need to gain or lose 1 or 2 electrons to be stable
• Ions- Forms of an atom that have gained or lost electrons
• Fills the outer shell of electrons• If electrons are gained, Ion is NEGATIVE
(ANION)• If electrons are lost, Ion is POSITIVE (CATION)