Adv Biology Chapter 2 Inorganic and Organic Chemistry

Levels of chemical organization Matter Atoms Elements, Molecules, and Compounds

Matter … is anything that occupies space and has mass. Molecules are particles of matter that are composed of one or more smaller units called atoms.

Classification of substances elements- are pure substances molecules-are united atoms forming larger chemical units compounds- are substances whose molecules have more than one element in them.

The Atom Name the parts of an atom 1. ? 2. ?? 3. ??? 4. ????

Parts of an atom Identify the charge of the particles of the atom –Proton –Electron –Neutron

Parts of an atom The charges of the particles of the atom: –Proton + positive –Electron - negative –Neutron 0 no charge

Elements A symbol is one or two letters used to represent an element –C for Carbon –Al for aluminum –S for sulfur –Cu for copper

Did you know? Elements are substances consisting of one type of atom, for example Carbon atoms make up diamond, and also graphite.Elementsatom Pure (24K) gold is composed of only one type of atom, gold atoms. Atoms are the smallest particle into which an element can be divided.

and Elements differ from each other in the number of protons they have, e.g. Hydrogen has 1 proton; Helium has 2.

Arranging the elements The elements are arranged by their atomic number which is equal to the number of protons for each element. The number of protons is equal to the number of electrons. The atomic mass is equal to the number of protons and neutrons in the nucleus. The periodic table is used in the study of chemistry.

The Periodic Table of the Elements Each Roman numeraled column on the label (at least the ones ending in A) tells us how many electrons are in the outer shell of the atom. Each numbered row on the table tells us how many electron shells an atom has. Thus, Hydrogen, in column IA, row 1 has one electron in one shell. Phosphorous in column VA, row 3 has 5 electrons in its outer shell, and has three shells in total.

Human elements… Four kinds of atoms make up 96% of the human body. The major elements include –oxygen –carbon –hydrogen –nitrogen There are traces of about 20 other elements in the body and known as trace elements

Compounds… are substances whole molecules have more than one element in them. Examples include –carbon dioxide –sodium chloride –water

Formula… for a compound contains the symbols for the elements in each molecule

Saccharin's chemical formula is C 7 H 5 O 3 NS Aspartame's chemical formula is C 13 H 18 O 5 N 2

Electron orbitals Negatively charged electrons surround the nucleus at a distance. They move about within certain limits called orbitals. Orbitals are arranged into energy levels (shells), depending on their distance from the nucleus.

Ionic bonds Ionic bonds are formed when atoms become ions by gaining or losing electrons.Ionic bonds ions Chlorine is in a group of elements having seven electrons in their outer shells. Members of this group tend to gain one electron, acquiring a charge of -1. Sodium is in another group with elements having one electron in their outer shells.

Covalent bonds Covalent bonds form when atoms share electrons.Covalent bonds Since electrons move very fast they can be shared, effectively filling or emptying the outer shells of the atoms involved in the bond. Such bonds are referred to as electron- sharing bonds. An analogy can be made to child custody: the children are like electrons and tend to spend some time with one parent and the rest of their time with the other parent.

Ways of representing covalent bonds.

Hydrogen bonds Hydrogen bonds result from the weak electrical attraction between the positive end of one molecule and the negative end of another.Hydrogen bonds Individually these bonds are very weak, although taken in a large enough quantity, the result is strong enough to hold molecules together or in a three- dimensional shape.

Examples of hydrogen bonds

Chemical reactions and molecules Molecule versus Mixture: Molecules are compounds with elements in definite, fixed ratios. Those atoms are held together usually by one of the three bonds discussed above. For example: water, glucose, ATP.Molecules

Mixture ~ Molecule Mixtures are compounds with variable formulas/ratios of their components. For example: soil. Molecular formulas are an expression in the simplest whole-number terms of the composition of a substance. For example, the sugar glucose has 6 Carbons, 12 hydrogens, and 6 oxygens per repeating structural unit. The formula is written C 6 H 12 O 6.glucose