Chemical Bonding & Compounds Compounds

Molecule – a particle made up of 2 or more atoms bonded together Compound – a substance made up of 2 or more elements bonded together Ions - atoms with different numbers of electrons (makes them electrically charged & opposites attract.) (makes them electrically charged & opposites attract.) Chemical bonding occurs when electrons are: gained, lost, or shared

Formulas tell the type and number of atoms in a compound. Ex: water - H 2 O (2 hydrogen, 1 oxygen) salt - NaCl (1 Sodium, 1 Chlorine) salt - NaCl (1 Sodium, 1 Chlorine) Compounds have characteristics that differ from the individual elements. ex: H & O are highly combustible gasses; whereas, H 2 O is not. Sodium is highly explosive in water & chlorine is a green poisonous gas; whereas, salt is edible and dissolves in water. salt is edible and dissolves in water. Law of Conservation of Matter: Matter is neither created nor destroyed, it remains the same or is rearranged.

Ionic bonds: formed by gaining or losing electrons; then opposites attract Characteristics of ionic compounds include: crystal shape, high melting point, & high electrical conductivity.

Covalent bonds: formed by sharing electrons Characteristics of covalent compounds: low melting & boiling points, and poor conductors of electricity. Ionic and covalent bonding animation – YouTube Ionic and covalent bonding animation – YouTube

Covalent molecules can form single bonds (share 1 pair of electrons), double bonds (share 2 pairs), or triple bonds (share 3 pairs). Polar molecules having unequal sharing of electrons (ex. H 2 O) Nonpolar molecules have equal sharing of electrons. (ex. CO 2 ) (ex. CO) (ex. CO) Polar molecules melt at Polar molecules melt at higher temps than nonpolar.

Oxidation number tells how many electrons are gained, lost, or shared to become stable All metallic elements, plus Hydrogen & Boron tend to lose electrons when bonding with nonmetals. (they have few valence electrons, (they have few valence electrons, so they lose all of their valence electrons) so they lose all of their valence electrons) Nonmetals tend to gain electrons when bonding with metals. (they have many valence electrons, they will gain (they have many valence electrons, they will gain enough to equal 8. example: has 5, gains 3) enough to equal 8. example: has 5, gains 3) Nonmetals tend to share electrons when bonding with nonmetals. (ex; covalent bond H 2 O: = 8) Noble Gases do not form chemical bonds because they already have a full valence shell (8), so they neither gain, lose, nor share electrons.

Organic Compounds contain carbon. Carbon bonds easily because it has 4 electrons in its outer shell, so it can form 4 separate covalent bonds.

4 groups of organic compounds in living things 1.Carbohydrates: – composed of C, H, & O in a 1:2:1 ratio. C, H, & O in a 1:2:1 ratio. 2. Lipids: (fats) – composed of long chains of C, H, & O.

3. Proteins – composed of C, H, O, & N. 4. Nucleic Acids – composed of C, H, O, N, & P C, H, O, N, & P

Water (H 2 O ) is an essential compound for all life on Earth. Due to its unique structure, water has very good adhesion_(water sticks to surfaces) and cohesion (water sticks to water). cohesion (water sticks to water). This aids in capillary action in plant stems/roots. This aids in capillary action in plant stems/roots. Water is often referred to as the universal solvent because of its ability to dissolve many different substances. Since water molecules are polar they attract ions and the charged parts of molecules. A Wet Towel In Space Is Not Like A Wet Towel On Earth : Krulwich Wonders... : NPR A Wet Towel In Space Is Not Like A Wet Towel On Earth : Krulwich Wonders... : NPR