Introduction to Chemical Compounds

What is a chemical compound? A compound is a substance that is made of two or more elements that are chemically bonded together.

Chemical Formula is the combination of atomic symbols that represent the elements and their quantities in a compound. EX: O 2, H 2 O, CH 4. Care and Share Explain why CO is not Co? Answer CO is a compound gas, Carbon Monoxide and Co is the element Cobalt which is a metal.

How many Oxygen Atoms are in the compound O 2 ? Answer 2 Care and Share Break down the compound CH 3 CH 2 CH 3 into the elements and their quantities. Answer C: 3 and H: 8

Ca(OH) 2 1.What are the elements? 2.How many of each? Answer Ca: 1 O: 1 x 2 = 2 H: 1 x 2 = 2

Determine the elements and their quantities for the compound: Ba(NO 3 ) 2 Ba: 1 N: 2 x1 =2 O: 3 x 2 = 6

Compounds are built based on the number of valence electrons each element has. The Electron Dot Diagram for each element has a specific number of valence electrons, ranging from 1 to 8. The figures below depict a way to show the number of valence electrons in an element. Each dot stands for one valence electron.

Draw the Electron Dot diagram for Ca.

Ca

Chemical Bonds and Compounds

Polar and Nonpolar Covalent Molecules Care and Share What is the difference between a polar and non-polar covalent molecule?

Polar covalent molecules is a covalent bond where the share electrons are not shared equally causing by side being positive and the other negative. Remember that the highest electronegativity constant will be the taker of an electron and will be more negative. The atom with the lower electronegativity will be the giver and will be more positive. Nonpolar covalent molecules share the electrons equally (They have the same electronegativity constants) or the pulls from other atoms are equal and opposite.

Most atoms are more stable when they have eight valence electrons. OCTET RULE Being stable means having their outermost electron shell filled with electrons. In order to become more stable, one of two things can happen: Either the number of valence electrons increases to eight Or the atom gives up loosely held valence electrons Bonds & Stability

The elements are Mg and O What are the electron dot diagrams for these two elements?

Mg O Elements Mg and O Electron Dot Diagrams

Mg +2 O -2 Chemical Formula: MgO Electrons are pulled towards Oxygen This is an example of a polar molecule.

Why is F 2 non-polar covalent molecule? F 2 is a nonpolar covalent because the electronegativity charges are the same. F

CO 2 COO The electron pull is equal and opposite directions

CH 3 CH 3 Care and share Why is this a non-polar covalent bond? With your group come up dot diagram showing the electron pull direction. H H H C C H H H

CH 3 CH 3 Care and share Why is this a non-polar covalent bond? With your group come up dot diagram showing the electron pull direction. H H H C C H H H The C to C non-polar because they share the electrons equally. The C to H bonds are moving to C (Higher electronegativity) and they are equal and opposite on all 4 sides. Indicates the direction of the electron pull.

Other types of chemcial bonds. Double Bonds: Are bonds when the atoms share two pairs of electrons. Triple Bonds: Are bonds when atoms share three pairs of electrons.

Inert Gases (VIII) usually do not form bonds with other elements because there outer shell is filled with 8 electrons thus completing their Octet Rule.

Physical Characteristics of Ionic Compounds Hard Brittle High Melting Point and Boiling Points When dissolved in water or melted they can conduct electricity.

Physical Characteristics of Covalent Compounds Low Melting Point and Boiling Points When dissolved in water or melted they usually do not conduct electricity.