1. Chapter 2: The Chemistry of Life Section 1: The Nature of Matter
CCS Biology
Mr. Bogusch

2. Atoms Atoms – basic units of matter Atoms are made of three parts
Proton – positively charged subatomic particle
Neutron – subatomic particle with no charge
Electron – negatively charged subatomic particle
1/1840 mass of a proton
An atoms positive and negative charges even each other out which make the atom neutral

3. Atomic Models

4. Elements and Isotopes
Elements – pure substance that consist entirely of only one type of atom
Atomic number – number of protons
More than 100 elements are known and organized on the periodic table

5. Interactive Periodic Table of Elements

6. Elements and Isotopes
Isotope – atom of the same element that have different number of neutrons
Mass Number – total number of protons and neutrons
Radioactive Isotope – nuclei are unstable and break down at a constant rate over time.
Uses
Radiometric dating
Detect and treat cancer

7. Chemical Compounds
Compound – substance formed by the chemical combination of two or more elements in definite proportions
Chemical Formula Examples
NaCL, H2O

8. Chemical Compounds
The characteristics of compounds are usually different form the individual elements it is made of
For Example
H2O – Water – if you combine hydrogen gas and oxygen gas it can be explosive!
NaCl – Salt – sodium chloride – salt is essential to all living things
Na – Sodium – silver colored metal soft enough to cut with a knife that reacts explosively with water
Cl – Chlorine – poisonous gas used in WWI – chemical warfare
Hydrogen and Oxygen Balloons
Sodium and Water

9. Chemical Bonds
Ionic Bond – formed when 2 or more electrons are transferred from one atom to another
Ions – atoms that gain or lose an electron
For example
Na+ + Cl --- → NaCl
Positively charged + negatively charged = neutral charge

10. Ionic Bonding - NaCl

11. Chemical Bonds Covalent Bond – formed when atoms share electrons
Molecule – atoms joined together by covalent bonds
For example: H2O

12. Chemical Bonds
Van der Waals Forces – a weak chemical attraction between oppositely charged regions of nearby molecules
For Example: H2O, Tokay gecko

13. Chapter 2: The Chemistry of Life Section 2: Properties of Water

14. The Water Molecule
Found in liquid form over most of the Earth’s surface
Like most molecules, Water is neutral
H2O has 10 protons (positive) and 10 electrons (negative)
The protons and electrons balance each other out!

15. The Water Molecule
Polarity – a molecular with an uneven distribution of charge
Oxygen has 8 protons which attract electrons strongly, as a result most of water electrons are found near the oxygen atom making that side of the atom partially negative charged

16. The Water Molecule
Hydrogen Bonding - that attraction between a hydrogen atom with a partially positive charge with another atom with a partial negative charge
Because of their partial positive and negative charges, polar molecules can attract each other.
Because water is a polar molecule, it is able to form multiple hydrogen bonds, which account for many of water’s special properties.

17. The Water Molecule

18. The Water Molecule
Cohesion –attraction between molecules of the same substance
Water can attract itself forming “beads” of water
Cohesion also produces surface tension
Water molecules hydrogen bonds have a certain amount of strength
For example – spiders that can walk on water

19. Cohesion and Adhesion

20. The Water Molecule
Adhesion – the attraction between molecules of different substances
For example: water on glass

21. The Water Molecule Heat Capacity
Since there are multiple hydrogen bonds between water molecules it takes a large amount of energy to cause those molecules to move fast, which raises the temperature.
For example: large lakes and oceans retain heat even though the air will become colder. This protects against drastic change in temperature

22. Solutions and Suspensions
Mixture – a material composed of two or more elements or compounds that are physically mixed together but not chemically combined.

23. Solutions and Suspensions
Two types of mixtures that re combined with water are solutions and suspensions
Solutions- a substance that is evenly distributed in water
Solute – the substance that is dissolved
Solvent (water)– the substance in which the solute dissolves
Water’s polarity gives it the ability to dissolve both ionic and other polar molecules
Suspension – mixtures of water and nondissolved material

25. Acids, Bases, and pH Water molecules split to form ions
pH Scale – indicates the concentration of H+ ions in a solution
Range 0 – 14
Acids < pH of 7 (contain a high concentration of H+ ions)
Bases > pH of 7 ( contain a high concentration of OH- ions and a low concentration of H+ ions)
Neutral = 7 (contain no H+ ions or OH- ions “theoretically”)

26. Acids, Bases, and pH