1. CHEMICAL ELEMENTS AND COMPOUNDS
MATTER: made of chemical elements and compounds
WHAT IS MATTER?
MASS V. WEIGHT
MASS- THE AMOUNT OF MATTER IN AN OBJECT
WEIGHT-A MEASURE OF HOW STRONGLY AN OBJECT IS PULLED BY EARTH’S GRAVITY-VARIES WITH DISTANCE FROM EARTH’S CENTER
Are your mass
and weight
the same????

2. ELEMENTS FOR LIFE C O H N LIFE requires about 25 elements
C,O,H,N- make up 96% of living matter
ELEMENTS-made up of all the same type of atoms
COMPOUNDS-made of diff. Elements
C O H N

3. ATOMS AND MOLECULES ATOM-smallest unit of matter
3 particles in an atom:
Proton (+)
Neutron(0)
Electron(-)
**IF AN ATOM IS ELECTRICALLY NEUTRAL, THE # OF PROTONS = # OF ELECTRONS

4. ATOMIC NUMBER & ATOMIC WEIGHT
ATOMIC #= # of protons and electrons in an atom- lefthand lower subscript
ATOMIC MASS= # of protons and neutrons in an atom-lefthand superscript
WHAT IS THE ATOMIC MASS OF SODIUM???
23 Na 11

5. ISOTOPES
ISOTOPES-atoms of an element have the same atomic number but different atomic masses
They have the same number of protons, different number of neutrons
Some isotopes are radioactive;these are unstable atoms in which the nucleus decays emitting subatomic particles and/or energy as radioactivity
Half-life: time for 50% of radioactive atoms in a sample to decay

6. The energy level of electrons
Electrons-negatively charged particles
Energy-ability to do work
Potential energy-stored enegy
Electrons with the lowest potential energy are closest to the nucleus
Electrons gain energy as they move away from the nucleus

7. Energy con’t
Electrons may move from one energy level to another-they gain or lose energy equal to the difference in potential Energy between the old and new energy level

8. ELECTRON ORBITALS
ORBITAL-3d space where electrons are found the majority of the time

9. ENERGY LEVELS FIRST ENERGY LEVEL -has one “s” orbital
Holds a max of 2 electrons
SECOND ENERGY LEVEL
-has one “s” orbital and 3 “p” orbitals
-holds a max of 8 electrons
HIGHER ENERGY LEVELS
-has S AND P ORBITALS

10. ELECTRON CONFIGURATIONS

11. CHEMICAL PROPERTIES OF AN ATOM
VALENCE ELECTRONS-the electrons in the outermost shell. They determine how an atom will react
OCTET RULE - valence shell is complete when it contains eight electrons
*** if an atom does not have a full outer shell it is reactive and will form bonds with other unstable atoms

12. CHEMICAL BONDING
CHEMICAL BONDS-attractions that hold molecules together
1) COVALENT BONDS-formed by atoms that SHARE electrons--these are STRONG bonds

13. BONDING
SINGLE COVALENT BOND-sharing of a single pair of valence electrons
DOUBLE COVALENT BOND-sharing of two pairs of valence electrons
COMPOUND-A substance made of 2 or more elements combined in a fixed ratio
Ex: water (H20) , methane(CH4)

14. COVALENT BONDING

15. POLAR AND NONPOLAR COVALENT BONDS
ELECTRONEGATVITY- an atom’s ability to attract and hold electrons
The more electronegative an atom, the more strongly it attracts shared electrons
Scale determined by Linus Pauling:
O S and C - 2.5
N P and H - 2.1
NONPOLAR COVALENT BOND-fomed by an equal sharing of electrons-when electroneg of both atoms is about the same

16. POLAR COVALENT BONDS
COVALENT BONDS FORMED BY AN UNEQUAL SHARING OF ELECTRONS
CHECK OUT THE NEXT EXAMPLE OF A WATER MOLECULE
THE OXYGEN IS STRONG ELECTRONEG., SO ELECRONS SPEND MORE TIME AROUND THE OXYGEN THAN THE HYDROGENS
THIS GIVE THE OYGEN A SLIGHT NEG CHARGE AND THE HYDROGENS A SLIGHT POSITIVE CHARGE

17. POLAR COVALENT BONDS

18. POLAR AND NONPOLAR COVALENT BONDS

19. IONIC BONDS ION-charged atom or molecule
ANION-an atom that has gained one or more electrons and as become negatively charged
CATION-an atom that as lost one or more electrons and has become positively charged

20. IONIC BONDING
IONIC BOND- bond formed by the electrostatic attraction after the transfer of an electron from one atom to another
OPPOSITIES ATTRACT-opposite charged of the atoms create the ionic bond
IONIC COMPOUNDS-are called salts-will dissolved easily in water

21. IONIC BONDS

22. WEAK BONDS IMPORTANT IN CELL CHEMISTRY
BIOLOGICALLY IMPORTANT WEAK BONDS INCLUDE:
HYDROGEN BONDS, IONIC BONDS
THEY MAKE CHEMICAL SIGNALLING POSSIBLE IN LIVING ORGANISMS BECAUSE THEY ARE ONLY TEMPORARY ASSOCIATIONS
CAN FORM BETWEEN MOLECULES OR BETWEEN DIFF PARTS OF A SINGLE LARGE MOLECULE
HELP STABILIZE THE 3-d SHAPE OF LARGE MOLECULES (DNA AND PROTEINS)

23. HYDROGEN BONDS
HYDROGEN BONDS-formed by the charge attraction when a H+ atom covalently bonded to one atoms is attracted to another atom
A weak bond
Is a charge attraction between oppositely charged portions of polar molecules
VAN DER WAALS INTERACTIONS
Weak interactions that occur between atoms and molecules that are very close together and result from charge symmetry in electron clouds

24. HYDROGEN BONDING IN DNA
HYDROGEN BONDING IS AT THE VERY BASIS OF THE HUMAN GENOME

25. MOLECULAR FUNCTION IS RELATED TO SHAPE
A molecule has a characteristic size and shape
The function of many molecules depends on its shape
Ex:: Insulin causes glucose uptake into liver and muscle cells because the shape of insulin molecule is recognized by specific receptors on the target cell

26. MOLECULER SHAPE RELATES TO ITS FUNCTION

27. CHEMICAL RXNS MAKE AND BREAK CHEMICAL BONDS
CHEMICAL REACTIONS-the process of making and breaking chemical bonds leading to changed in matter
Process where reactants undergo changes into products
Matter is conserved and reactants are only rearranged to form products
Most reactions are reversible
CHEMICAL EQUILIBRIUM-when forward and reverse rates of reactions are equal