1. The student is expected to: 4B investigate and explain cellular processes, including homeostasis, energy conversions, transport of molecules, and synthesis of new molecules and 9A compare the structures and functions of different types of biomolecules, including carbohydrates, lipids, proteins, and nucleic acids

2. KEY CONCEPT Living things consist of atoms of different elements

3. Living things consist of atoms of different elements.
An atom is the smallest basic unit of matter.
An element is one type of atom.
Hydrogen atom (H) H O
Oxygen atom (O)

4. An atom has a nucleus and electrons.
The nucleus has protons and neutrons.
Electrons are in energy levels outside nucleus.
Oxygen atom (O)
Nucleus: 8 protons (+) 8 neutrons
outermost energy level: 6 electrons (-)
inner energy level: 2 electrons (-)

5. Protons with a positive charge
Electrons with a negative charge
Neutrons with a neutral charge/ no charge

6. Elements Elements are pure substances made up of one kind of atom.
All atoms of that element look just the same, with the same number of protons, neutrons (average), and electrons.
The number of protons indicates the type of atom.

7. O A compound is made of atoms of different elements bonded together.
water (H2O) O H _ +

8. A compound is made of atoms of different elements bonded together.
water (H2O)
carbon dioxide (CO2)

9. A compound is made of atoms of different elements bonded together.
water (H2O)
carbon dioxide (CO2)
many other carbon-based compounds in living things

10. Ions form when atoms gain or lose electrons.
An ion is an atom that has gained or lost one or more electrons.
positive ions form when atoms lose electrons
negative ions form when atoms gain electrons
Ionic bonds form between oppositely charged ions.
Sodium atom (Na)
Chlorine atom (CI)
Sodium ion (Na+)
Chloride ion (CI-)
Na loses an electron to CI
ionic bond
gained electron

11. Atoms share pairs of electrons in covalent bonds.
A covalent bond forms when atoms share a pair of electrons.
multiple covalent bonds
diatomic molecules
covalent bonds
Oxygen atom (O)
Carbon atom (C)
Carbon dioxide (CO2 )

12. Isotopes are uncharged atoms with a different atomic mass than the common element.
Count the number of neutrons in each isotope of carbon above

13. Isotopes
Carbon Carbon-14
P = P = 6
N = N = 8
e = e = 6
Carbon-14 has two more neutrons than Carbon-12. it’s nucleus has a greater mass.

14. Some isotopes are radioactive and break down at a constant rate over time.
We can use these to help date rocks and fossils, use them to treat cancers, and use them as biological markers within an organism

15. The student is expected to:
4B investigate and explain
cellular processes, including
homeostasis, energy conversions,
transport of molecules, and
synthesis of new molecules
and
9A compare the structures and
functions of different types of
biomolecules, including
carbohydrates, lipids, proteins, and
nucleic acids

16. Life depends on hydrogen bonds in water.
Water is a polar molecule.
Polar molecules have slightly charged regions. O H _ +
Nonpolar molecules do not have charged regions.
Hydrogen bonds form between slightly positive    hydrogen atoms and slightly negative atoms.

17. Polarity refers to the unequal sharing of electrons.
Although water is an electrically neutral molecule it is does exhibit polarity.
Polarity refers to the unequal sharing of electrons.
Polarity creates partial positive charges and partial negative charges on each water molecule.
The electrons spend more time around oxygen than they do around Hydrogen.
Hydrogen is NAKED!

18. POLARITY
The shared electrons between oxygen and hydrogen tend to spend more time orbiting the oxygen atom giving it a unequal charge distribution e
In a water molecule, are the electrons more likely to be near the oxygen nucleus or the hydrogen nucleus? _______________
Oxygen nucleus

19. The oxygen end gets a partial negative charge
Hydrogen end gets a partial positive charge

20. Negative charges are attracted to positive charges.
In a water molecule the negative oxygen end is attracted to the positive hydrogen end of another molecule
This creates a weak Hydrogen Bond between water molecules

21. Water can form multiple hydrogen bonds between molecules
Hydrogen bonding
the charges in parentheses are
partial charges H O
(-)
(+)
Water can form multiple hydrogen bonds between molecules

22. Hydrogen bonds are responsible for some important properties of water.
high specific heat
Cohesion
a)Surface tension
Adhesion
b)meniscus

23. Cohesion
Cohesion is an attraction between molecules of the same substance.
Water is very cohesive because of hydrogen bonding.

24. Cohesion creates surface tension
A measure of how difficult it is to stretch or break the surface of a liquid.
The weight of the paper clip isn’t enough to break the weak hydrogen bonds between the water molecules

25. Water striders rely on cohesion between water molecules

26. Adhesion
Adhesion is an attraction between molecules of different substances.
Water also sticks to, or adheres, to other surfaces well. This is why a meniscus forms when you are measuring liquid.

27. Capillary action
Cohesion and adhesion combined allows water to move up certain materials.
This is how plants get water from the ground up through their stems

28. Polarity also affects Solubility
Solubility refers to the ability of one substance (solute) to dissolve in another (solvent)

29. Many compounds dissolve in water.
A solution is formed when one substance dissolves in another.
A solution is a homogeneous mixture.
Solvents dissolve other substances.
Solutes dissolve in a solvent.
solution

30. Solubility Polar substances can dissolve other polar substances.
Non-polar substances dissolve other non-polar substances.
Polar substances and non-polar substances do not mix.

31. “Like dissolves like.” Polar solvents dissolve polar solutes.
Nonpolar solvents dissolve nonpolar solutes.
Polar substances and nonpolar substances generally remain separate.

32. Water is a polar molecule
Oil is a non-polar molecule
Oil and water do not mix for this reason

33. Some compounds form acids or bases.
An acid releases a hydrogen ion when it dissolves in water.
high H+ concentration
pH less than 7
more acidic
stomach acid pH between 1 and 3

34. A base removes hydrogen ions from a solution.
low H+ concentration
pH greater than 7
bile pH between 8 and 9
more basic

35. A neutral solution has a pH of 7.
pure water pH 7

36. Myth: All acids are harmful and will burn your skin.
Busted: Not all acids cause burns…some examples are lemon juice and vinegar

37. Myth: Bases are safe to handle
Busted: Lye or Sodium Hydroxide is very dangerous