Basic Chemistry Applied Biology

Basic Vocab MatterMatter: anything that occupies space and mass. (ex. desk, pencil, cookie….) ElementElement: pure substance that can’t be broken down into other substances by chemical means.(Ex. gold, silver, oxygen) CompoundCompound: substance containing 2 or more elements that are chemically combined in a fixed ratio. (Ex. H 2 O, NaCl……)

COMPOUNDS What is a compound? Examples of compounds? O HH _ ++ A compound is made of ATOMS of different elements bonded together.

The elements in your body. All of the elements represented are essential to life. The 4 main elements in your body: C – carbon H-hydrogen O-oxygen N-nitrogen

The properties of compounds differ from the individual elements Sodium (Na) + Chlorine (Cl)= NaCl (salt)

Atoms “atomos” – “indivisible” An atom is the smallest basic unit of matter. Smallest possible particle of an element –Ex: oxygen atom, gold atom –Many atoms of the same type make up the element Atoms are made of smaller parts called subatomic particles.

Subatomic Particles Proton: positive electrical charge (+) Electron: negative electrical charge (-). e-, least mass Neutron: electrically neutral – no charge Oxygen atom (O) Nucleus: 8 protons (+) 8 neutrons outermost energy level: 6 electrons (-) inner energy level: 2 electrons (-)

Atom vs. Element Atom: -no observable traits (like Element) -no melting or boiling points, density, color An atom has an atomic number

An element’s physical and chemical properties depend on the number and arrangement of subatomic particles. Nucleus: core of an atom –protons and neutrons –e- found in cloud around nucleus travel at great speeds attracted to (+) ATOMIC # = Number of protons NEUTRAL elements will have same # of protons and electrons

Figure 4-4 This model of a helium atom indicates the number of each kind of subatomic particle it contains. Though no visual model can accurately show an atom's structure, models can help you in understanding certain aspects of an element's chemical behavior.

PRACTICE ElementAtomic ## of Protons # of Electrons Hydrogen111 Calcium20? Carbon??6 Oxygen8??

Electrons and Reactivity e- belong to different energy levels e- fill the 1 st levels 1 st –1 st level = 2 e- –2 nd level = 8 e- –Partially filled levels make atoms more reactive; they want to fill their highest occupied energy levels 4.2 online

Chemical Bonds join atoms to one another IONIC BOND- one atom transfers an electron to another atom –Atoms ‘want’ their outermost layer to be filled –Ex. Table salt (NaCl) (now are IONs)

Chemical Bonds join atoms to one another COVALENT BOND- two atoms share electrons MOLECULE = two or more atoms held together by covalent bonds

O HH _ ++ Life depends on hydrogen bonds in water. Water is a polar covalent molecule. Polar molecules have slightly charged regions. Water is a polar covalent molecule. Polar molecules have slightly charged regions. Nonpolar molecules do not have charged regions. Oxygen atom (-) Hydrogen atoms (+) Hydrogen bonds: form between slightly positive hydrogen atoms and slightly negative oxygen atoms.

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. (H2O) –Solutes dissolve in a solvent. (Salt or sugar) solution

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

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

A neutral solution has a pH of 7. What are some examples of Acids & Bases? pure water pH 7