Molecule Fundamentals Biology Sumner HS Biology Sumner HS

Molecules = Level up! When atoms combine, their properties contribute to the formation of a molecule with new properties. Atoms form bonds with other atoms: electron connections/interactions that keep them together. What happens to the electrons determines the nature of the bonds. When atoms combine, their properties contribute to the formation of a molecule with new properties. Atoms form bonds with other atoms: electron connections/interactions that keep them together. What happens to the electrons determines the nature of the bonds.

Chemical Formula Notation Carbon Dioxide CO 2 Carbon Oxygen Subscript # = # of that atom in molecule How many atoms?

Chemical Formula Notation Ethane C2H6C2H6C2H6C2H6 How many atoms?

Chemical Formula Notation Water 6H 2 O “Multiplier” Shows how many molecules are present How many atoms?

H 2 O 4CO 2 6O 2 2CH 4 3NH 3 3Co 6CH 4 O C 4 H 8 O 2 2NH 5 CO 2 6C 6 H 12 O 6 H 2 O 4CO 2 6O 2 2CH 4 3NH 3 3Co 6CH 4 O C 4 H 8 O 2 2NH 5 CO 2 6C 6 H 12 O 6

How many atoms? H 2 O =3 4CO 2 =12 6O 2 =12 2CH 4 =10 3NH 3 =12 3Co =3 6CH 4 O =36 C 4 H 8 O 2 =14 2NH 5 CO 2 =18 6C 6 H 12 O 6 =144 H 2 O =3 4CO 2 =12 6O 2 =12 2CH 4 =10 3NH 3 =12 3Co =3 6CH 4 O =36 C 4 H 8 O 2 =14 2NH 5 CO 2 =18 6C 6 H 12 O 6 =144

Molecular bonds Remember, atoms like to have a “full” shell of electrons. Can achieve that by sharing electrons with each other. Electrons begin to spend time around both nuclei. This is a covalent bond. Remember, atoms like to have a “full” shell of electrons. Can achieve that by sharing electrons with each other. Electrons begin to spend time around both nuclei. This is a covalent bond.

Forming Covalent Bonds

EO Wilson’s Life on Earth Covalent Bonds pg. 48

Where can they share? Atoms will share electrons to fill open “slots” in a shell. Atoms won’t share in spots where there is a full pair of electrons. Atoms will share electrons to fill open “slots” in a shell. Atoms won’t share in spots where there is a full pair of electrons.

Some examples H 2 O = water: 2 hydrogen, 1 oxygen O 2 = oxygen (normal gas molecule): 2 oxygen. CH4 = methane (natural gas): 1 carbon, 4 hydrogen NH3 = ammonia: 1 nitrogen, 3 hydrogen H 2 O = water: 2 hydrogen, 1 oxygen O 2 = oxygen (normal gas molecule): 2 oxygen. CH4 = methane (natural gas): 1 carbon, 4 hydrogen NH3 = ammonia: 1 nitrogen, 3 hydrogen

PIT Box: Summarize Covalent Bond Structure

Covalent Bond Properties “Sharing” in covalent bonds leads to a strong bond. Usually needs energy input (or the help of an enzyme) to be broken. Spark, fire, digestive enzymes Provides structural strength. Collagen proteins in tendons. Can store energy. Carbohydrates, fats, etc. “Sharing” in covalent bonds leads to a strong bond. Usually needs energy input (or the help of an enzyme) to be broken. Spark, fire, digestive enzymes Provides structural strength. Collagen proteins in tendons. Can store energy. Carbohydrates, fats, etc.

Campbell’s Biology Ch 2: Covalent Bonds

PIT Summary: Covalent Bonds Come from electrons being shared The attraction of the nuclei for the electrons in shared orbit is what holds the atoms together. This forms a strong bond. Hard to break Structural strength A form of potential energy. Come from electrons being shared The attraction of the nuclei for the electrons in shared orbit is what holds the atoms together. This forms a strong bond. Hard to break Structural strength A form of potential energy.