Objectives Describe how a compound differs from an element. Identify parts of a chemical formula. Explain why chemical bonding occurs. CLE 3202.1.7 Construct chemical formulas for common compounds.

Chemical Bonds

Stability in Bonding A. Some elements combine chemically and no longer have the same properties they did before forming a compound

Stability in Bonding B. Compounds make up most of matter because arrangements of electrons in most atoms make them chemically unstable.

Stability in Bonding C. Stable atoms must have 8 electrons. Atoms share, gain or lose electrons to become more stable.

Stability in Bonding D. A chemical bond forms when an atom gains, loses or shares electrons.

Stability in Bonding E. A chemical formula tells what elements make up a compound and the ratio of the atoms of those elements.

Stability in Bonding 1. A(n) chemical formula is composed of symbols and subscripts indicating the number of atoms of an element in a compound

Stability in Bonding Iron oxide water sulfuric acid (rust) (battery acid) Fe2O3 H2O H2SO4 2:3 2:1 2:1:4 HC2H3O2 vinegar 1:2:3:2 acetic acid

Stability in Bonding F. An atom is chemically stable if its outer energy level is completely filled with electrons. Noble (inert gases) gases are chemically stable. He – 2 atoms Most others – 8

Stability in Bonding G. Atoms form compounds when the compound is more stable than the separate atoms.

Stability in Bonding 1. Noble gases are more chemically stable than other elements because they have a complete outer energy level.

Stability in Bonding 2. Elements that do not have full outer energy levels are more stable in compounds.

Stability in Bonding 3. Atoms can lose, gain, or share electrons to get a stable outer energy level.

Stability in Bonding 4. A chemical bond is the force that holds atoms together in a compound.

Why do elements form compounds? To become more chemically stable by getting a complete outer energy level

Objectives Describe how a compound differs from an element. Identify parts of a chemical formula. Explain why chemical bonding occurs. CLE 3202.1.7 Construct chemical formulas for common compounds.

Types of Bonds 19-2

Objectives Given a periodic table, determine the oxidation numbers. Distinguish between ionic and covalent bonds. CLE 3202.1.7 Construct chemical formulas for common compounds. CLE 3202.1.6 Distinguish between common compounds formed by ionic and covalent bonds.

Types of Bonds Ionic Bonds 1. Atoms can gain or lose electrons in the outer energy level.

Ionic Bonds 2. When the number of electrons is different from the number of protons, the atom has an electrical charge.

Ionic Bonds 3. The name of this charged particle is ion.

Ionic Bonds When an atom loses an electron, it becomes a positively charged ion; a. A superscript indicates the charge.

Ionic Bond 5. When an atom gains an electron, it becomes a negatively charged ion. Na+ Cl-

Types of Bonds B. An ionic compound is held together by the ionic bond – the force of attraction between opposite charges of the ions.

Ionic Bond-Transfer

Ionic Bond-Transfer

Ionic Bond 1. The result of this bond is a(n) neutral compound.

Ionic Bond 2. The sum of the charges on the ions is zero.

Types of Bonds C. Molecules are neutral particles formed as a result of sharing electrons.

Covalent Bond 1. A covalent bond is the force of attraction between atoms sharing electrons.

Covalent Bond 2. Atoms can form double or triple bonds depending on whether they share two or three pairs of electrons.

Covalent Bond 3. The covalent compound has a complete outer energy level.

Triple Bonds-Nitrogen

Covalent Bond Each hydrogen atom shares one of its electrons with the oxygen atom. All atoms have a complete outer energy level. The entire molecule is neutral

Covalent Bond 4. Electrons shared in a molecule are held more closely to the atoms with the larger nucleus.

Covalent Bond 5. A polar molecule has one end that is slightly negative and one end that is slightly positive, although the overall morecule is neutral.

Polar Covalent Bond Water

Covalent Bone 6. In a(n) nonpolar molecule, electrons are shared equally.

Non-polar Covalent Bond Methane

What two types of atomic bonds form and how do they differ? Ionic bonds form when atoms lose or gain electrons; covalent bonds form when atoms share electrons.

Objectives Given a periodic table, determine the oxidation numbers. Distinguish between ionic and covalent bonds. CLE 3202.1.7 Construct chemical formulas for common compounds. CLE 3202.1.6 Distinguish between common compounds formed by ionic and covalent bonds.

Writing Formulas and Naming Compounds 19-3

Writing Formulas & Naming Compounds Chemists use symbols from the periodic table to write formulas for compounds.

Writing Formulas & Naming Compounds Binary compound – composed of two elements.

Binary Compound

Writing Formulas & Naming Compounds Oxidation number – how many electrons an atom has gained, lost, or shared to become stable.

Writing Formulas & Naming Compounds oxidation numbers

Writing Formulas & Naming Compounds Use oxid # & their least common multiples to write formulas.

Writing Formulas & Naming Compounds When writing formulas, remember that the cmpd is neutral.

Writing Formulas & Naming Compounds A formula must have the correct number of + & - ions so the charges balance.

Writing Formulas & Naming Compounds Use the name of the 1st element, the root name of the 2nd element, and the suffix (-ide) to write the name of a binary ionic cmpd.

Writing Formulas & Naming Compounds Polyatomic ion -- + or – charged, covalently bonded group of atoms.

Common Polyatomic Ions

Writing Formulas & Naming Compounds The cmpd contains three or more elements.

Writing Formulas & Naming Compounds To write names, write the name of the + ion 1st; then wrtie the name of the - ion.

Writing Formulas & Naming Compounds To write formulas, use the oxid #, their least common multiple, and put () around the polyatomic ion before adding a subscript.

Writing Formulas & Naming Compounds Hydrate – compoud with water chemically attached to its ions.

Writing Formulas & Naming Compounds Name binary covalent cmpds by using prefixes to indicate how many atoms of each element are in the cmpd.

Prefixes

What is a binary compound? One that is formed from two elements.

Alkali Metals

Alkaline Earth Metals

Boron Group

Nitrogen Group

Halogens

Noble Gases