1. How Matter is Organized
All living things consist of matter.
Matter is anything that occupies space.
mass is the amount of matter in any object.
weight is the force of gravity acting on matter.
In outer space, weight is close to zero, but mass remains the same as on Earth.
States of matter
Solid – has definite shape and volume
Liquid – has definite volume, changeable shape
Gas – has changeable shape and volume

2. The Organization of Matter
An element is a pure substance that can’t be broken down into simpler substances by ordinary chemical or physical techniques
All matter (anything that occupies space and has mass) is composed of elements and combinations of elements
Ninety-two different elements occur naturally on Earth – other artificial elements have been synthesized in the laboratory

3. Common Elements in Living Organisms

4. Elements found in biological molecules

5. Atomic Structure Each element consists of one type of atom
Each atom consists of an atomic nucleus surrounded by fast-moving, negatively-charged electrons
Atomic nuclei contain positively charged protons – the number of protons (atomic number) identifies an element
The nuclei of all atoms (except hydrogen) also contain uncharged neutrons

6. Atomic Structure

7. Atomic Number and Mass Number
Atomic number = # protons
Each element has its own number of protons
Carbon has 6 protons. Oxygen has 8.
If you change the number of protons you change the element
If you add another proton to carbon it will have 7 which makes it nitrogen
Mass = # protons + # neutrons
Different masses of the same element are called isotopes (isotopes differ in # of neutrons; unstable isotopes decay and emit particles until they are stable, they are radioactive isotopes)

8. Isotopes of Carbon

9. Focus On Applied Research
Scans of human thyroid glands after iodine-123 was injected into the bloodstream
Radioactive iodine becomes concentrated in the thyroid gland

10. Compounds
Molecules whose component atoms are different (such as carbon dioxide) are called compounds
The chemical and physical properties of compounds are typically distinct from those of their atoms or elements
Example: Hydrogen (H) and oxygen (O) – the elements that form liquid water (H2O) – are both highly flammable gases

11. Electron Shells
Within an atom, electrons are found in regions of space called energy levels or shells
Maximum # of electron in a shell: 2n2 (‘n’ is the number of shell; n = 1, 2, 3, 4…….)
The arrangement of electrons in the shells is known as electronic configuration of an atom.
Sodium has 11 electron; so the electronic configuration of a carbon atom is 2, 8, 1
Chlorine has 17 electron; so the electronic configuration of a carbon atom is 2, 8, 7

12. Chemical Bonds and Chemical Reactions
The three most important chemical linkages in biological molecules are ionic bonds, covalent bonds, hydrogen bonds.
Chemical reactions occur when atoms or molecules interact to form new chemical bonds or break old ones
Ionic bonds result from electrical attractions between atoms that gain or lose valence electrons completely
A positively charged ion (one that has lost an electron), such as Na+, is called a cation
A negatively charged ion (one that has gained an electron), such as Cl--, is called an anion

13. Formation of an Ionic Bond

14. Covalent Two atoms share their outer electrons forming a bond
H2O, CO2, NH3, O2 are held together by covalent bonds

15. Intermolecular Forces
Polar molecules have a slightly positive end and a slightly negative end
Polar molecules form weak polar bonds with other polar molecules
Polar molecules containing hydrogen will form hydrogen bonds with other polar molecules.
Water is a polar molecule.

16. Water is important to life
Forms hydrogen bonds with itself and other polar molecules (Hydrophilic)
Forms a solution for many chemical reactions inside our cells
Moderates temperature
Required for photosynthesis

17. Inorganic Compounds & Solvents
Most of the chemicals in the body are compounds
Inorganic compounds
usually lack carbon & hydrogen and are structurally simple
water, carbon dioxide (a by-product of cell metabolism), oxygen (important in metabolic reaction,) acids, bases and salts
Organic compounds
contain carbon & hydrogen
always have covalent bonds

18. Water Water makes up about 2/3 of total body weight.
Aqueous solution containing +/- ions will conduct electrical current. + & - move toward each other.
Homogenous mixture of two or more substances is called, solution. The medium in which other atoms, ions molecules are dispersed is called the solvent. The dispersed substances are the solute.
When water is the solvent, the solution is known as aqueous solution.

19. Acids and Bases
Acids are proton donors that release H+ (and anions) when they are dissolved in water, increasing the H+ concentration
Example: Hydrochloric acid (HCl) dissociates into H+ and Cl– when dissolved in water (HCl ↔ H+ + Cl– )
Bases are proton acceptors that reduce the H+ concentration of a solution; most release a hydroxide ion (OH–) and a cation
Example: NaOH → Na+ + OH– ; excess OH– combines with H+ to produce water (OH– + H+ → H2O)

20. pH Acids are molecules that give up a positive hydrogen ion (H+)
The concentration of H+ ions in a water solution, compared with the concentration of OH– ions, determines the acidity of the solution
Acidity is measured using the pH scale: ranging from 0 to 14 – based on logarithms of the number of H+ ions in solution: pH = –log10[H+]
Acids are molecules that give up a positive hydrogen ion (H+)
Bases are molecules that accept a positive hydrogen ion (H+)
How readily an atom accepts or donates a hydrogen is indicated by its pH
Acids < pH < 7
Bases < pH < 14
Water pH = 7 (Neutral)

21. pH Scale

22. Buffer Systems of the Body
Body fluids vary in pH but the range of each is limited and is maintained by a variety of buffering systems.
gastric juice 1.2 to 3.0; saliva 6.35 to 6.85; bile 7.6 to 8.6 and blood 7.35 to 7.45
Buffer: that resists the change in pH
Buffers stabilize the pH of a solution by removing or replacing hydrogen ions.
carbonic acid - bicarbonate buffer system

23. TYPES of chemical reactions
Decomposition AB A + B
Synthesis A + B  AB
Exchange AB + CD  AC +BD
HCl + NaHCO3  H2CO3 + NaCl
Decomposition- catabolism, breaking molecules in two or more substances; usually exergonic, releases heat.
All the synthesis reactions in the body together are called anabolism
Two or more atoms, ions or molecules combine to form new & larger molecules
Usually are endergonic because they absorb more energy than they release