1. The Chemical Basis of Life
Chapter 4
The Chemical Basis of Life

2. Matter
All living things are made up of matter – anything that has mass and takes up space
Water, air, and your body are different substances but are all made up of matter

3. NOT IN PACKET MATTER – solid, liquid, gas, plasma MOLECULES ATOMS
SUBATOMIC PARTICLES
Protons
Electrons
Neutrons

4. Mass – the amount of matter an object has
Mass vs Weight
Mass – the amount of matter an object has
Weight – the amount of mass an object has plus the force of gravity

5. Matter exists in 4 different states Solid – definite shape and volume
States of Matter
Matter exists in 4 different states
Solid – definite shape and volume

6. Liquid – definite volume, not shape
Gas – no definite shape or volume

7. Plasma - high temperature ionized gas

8. Elements
Element – substance made up of the same type of atoms that can not be broken down chemically into a simpler kind of matter

9. 25 elements are important to living things
4 make up 96% of the living matter in your body
Oxygen, Carbon, Hydrogen, Nitrogen

10. Trace elements – elements that make up less than
Trace elements – elements that make up less than .01 percent of body mass, but critical to health
Ex. 1.5 mg of Iodine each day – affects thyroid gland
.004% Iron – important for O2 in your blood

11. Compounds
Compound – substance containing 2 or more elements that are chemically combined in a fixed ratio
Ex. H2O

12. Physical and chemical properties differ between the elements that make up the compound and the compound itself
Ex. Oxygen and Hydrogen = gases
Combined = liquid

13. Atom – smallest possible particle of an element
Greek atoms = invisible
Nucleus – consists of protons and neutrons and makes up most of the mass of the atom

14. Proton – positively charged particle
Neutron – neutral; particle with no charge
Electron – high energy, negatively charged particle with little mass

15. Each orbit holds a certain amount of electrons
Atoms
Orbital – 3D region around a nucleus that indicates the probable location of an electron
Each orbit holds a certain amount of electrons

16. 1st orbit – 2 e
2nd orbit – 8 e
3rd orbit – 8 e

17. Ex. He and Ne both have 8 e in their outer orbits
Atoms
In order to be stable, an atom must have its outer orbit filled with electrons
Ex. He and Ne both have 8 e in their outer orbits

18. Atoms have the same number of protons (+) as electrons (-), therefore, an atom is neutral

19. Periodic Table – chart that summarizes and organizes the elements
Atoms
Periodic Table – chart that summarizes and organizes the elements
Chemical symbol – letters

20. Atomic number – number of protons an atom has
Mass number – total number of protons + neutrons
Ex: F 9 protons 10 neutrons = 19 atomic mass

21. Isotopes
Isotopes – atoms of the same element that have the same number of protons, but different number of neutrons

22. Radioactive Isotope – one in which the nucleus decays over time, giving off radiation in the form of matter and energy
Used in research and in medicine

23. Ionic Bonds
Ionic bond – the attractive force between oppositely charged ions which form when electrons are transferred from one atom to another

24. Ion – electrically charged atom or molecule
Ex. NaCl

25. Ex. Water Oxygen 6 electrons needs two Hydrogen
Covalent Bonding
Covalent bond – forms when two atoms share one or more pairs of electrons
Ex. Water Oxygen 6 electrons needs two Hydrogen

26. Molecule – 2 or more atoms held together by a covalent bond
Molecules
Molecule – 2 or more atoms held together by a covalent bond
Ex. H20 or O2

27. Chemical formula - #’s and types of atoms
Models of Molecules
Chemical formula - #’s and types of atoms
Structural formula – how the atoms are linked by bonds
Space filling model – 3-D model with colored spheres

28. Reactants – starting materials for a rxn
Chemical Reactions
Chemical Reactions – breaking of old and formation of new chemical bonds resulting in a new substance
Reactants – starting materials for a rxn
Products – ending materials in a rxn

30. Hydroxide ion = OH- Hydronium ion = H+
Acids, Bases, and pH
H2O H+ + OH-
Hydroxide ion = OH- Hydronium ion = H+

31. Acid – solution with more H+
Ex. HCl
Base – solution with more OH-
Ex. NaOH

32. pH Scale
pH scale – scale range from 0-14 that describes how acidic or basic a solution is
0-6 acid 7 neutral base

33. Buffer – substances that cause a solution to resist changes in pH
Important because the slightest change in pH can be harmful to organisms
Ex. Blood

34. On the back of your paper write:
Acids Neutral Base