Chemical Bonds Ch 5 Summary The protons determines

Chemical Bonds

Ch. 5 Summary The protons determines the type of element, while the electrons determine the reactivity of the element. If the protons and electrons are the same, it is neutral. All atoms would rather be stable, with 8* valence electrons as shown in Electron Dot Diagrams. Elements with the same number of valence electrons form the families on the periodic table. Ionic bonding involves gaining / losing electrons forming compounds between metals and nonmetals. Covalent bonding involves sharing electrons between nonmetals forming molecules, which are either polar or non-polar. In a polar bond, one atom pulls more on the electron, giving it have positive and negative “pole”. Nonpolar bonds equally shared electrons and are symmetrical.

Ch. 6 Vocab. Section 1 �Neutral �Electron Cloud �Energy Levels � 2, 8, 8… �Groups �Electron Dot Diagram �Valence Electrons (8*) �Chemical Bond Section 2 �Ions �Ionic Bonds �Compound �Covalent Bond �Molecule �Polar Bond �Uneven Sharing �Chemical Formulas

Counting Atoms in Formulas �Subscript = this tells the number of each atom in a compound. If there is no subscript we know that it is one atom. H 2 O : Hydrogen = 2, Oxygen = 1 �Parenthesis + Subscripts = sometimes there will be a parenthesis with a subscript after it. This means that you need to multiply all of the atoms in the parenthesis by the subscript outside of the parenthsis. Fe 3(PO 4)2 Fe= 3, P = 2, O = 8 * Superscript – shows the charge on an ion

Chemical Formulas Symbols = the type of atom Subscripts = the number of each atom Na. Cl Na= 1 H 2 O H= 2 CH 4 C= 1 Ibuprofen – C 3 H 8 O 2 C 10 H 10 C= 13 Cl = 1 O= 1 H= 4 H= 18 O= 2 Plavix – C 4 H 12 Cl. C 4 NC 4 O 2 SC 4 H 4 C=16 H=16 O=2 Cl=1 N=1 S=1

Periodic Table Shortcuts Table Group # 1 2 13 14 15 16 17 18 Valence 1 Electrons 2 3 Ion +1 +2 Formed 4 5 6 7 8 +4 +3 -3 -2 -1 na -4

Ionic Bonding We know that opposites attract, so oppositely charged ions will join together to form compounds. Ionic Bonding occurs between Metals and Non-metals

Ions �Electrons have negative charges. Protons have positive charges. An atom has no net charge while the protons and electrons are equal. �To form an ion, an element will gain or lose electrons until it has a complete outer energy level (HAPPY) �An element would rather be happy than neutral. �Gain electrons = net negative charge. �Lose electrons = net positive charge.

Compounds – opposites attract! �Positive Ions will attract Negative Ions. �A +1 ion will equally bond with a -1 ion. �A +2 ion will equally bond with a -2 ion. �What about when a +2 ion encounters a -1 ion?

Making Compounds = Making Elements Happy 1. 2. 3. 4. Compound E-Harmony Draw EDD Figure out the Charge that the 2 Ions will make. Multiply the + ions and – ions until they cancel. Write the formula with both charges and subscripts. Na + Cl

Ionic Bonding Practice Be + O Be + Cl

More Ionic Bonding Practice Na + P Al + Se

Polyatomic Bonding �This is the same principle as ionic bonding, just using more atoms. �Poly- many, several, much �Atomic – atom �Polyatomic Ion= Ion of multiple atoms. �OH�SO 4 -2 �PO 4 -3 �NO 3�These ions combine just like any other, except that you use parenthesis when adding multiple of these ions to something.

Polyatomic Ionic Bonding Practice K + OH- Mg + NO 3 -

Polyatomic Ionic Bonding Practice NH 4+ + CO 3 -2 Ca + PO 4 -3

Covalent Bonds �A covalent bond is when the two or more atoms share the electrons, instead of taking them from each other. �Co- with, together, joint �valent ~ valence electrons �Covalent Bonds are formed between nonmetals �When two or more atoms covalently bond, a molecule is formed. �Atoms that have 4 valence electrons are more likely to form covalent bonds than ionic bonds.

Making Molecules = Sharing the Lines xoxoxo 1. Draw the electrons as dots on the first element. 2. Draw the electrons as x’s on the 2 nd element. 3. Make a line connecting the x and dot to show a bond. Use 2 lines for double bonds. 4. Write the formula with subscripts. Br Br

Practice (using EDD) H O H F F When doing Covalent Bonding, the EDDs you show the bonds with lines.

Practice (using EDD) O C O HO Cl When doing Covalent Bonding, the EDDs you show the bonds with lines.

Polarity �Depending on how the electrons are shared, covalent bonds can be either polar, or non-polar. �Non-Polar = They share evenly. The molecule has symmetry. �Polar = One atom pulls more on the other creating a pole. One side is more positive while the other is more negative. The molecule has asymmetry.

Carbon Dioxide, CO 2 Non Polar Flourine, F 2 Non Polar Non-Polar = the molecule is symmetrical and the charges are evenly distributed.

Water, H 20 Polar Molecule Polar = there is a distinct ‘pole’ on both ends of the molecule, one positive, the other negative. This happens when the molecule is asymmetrical.

Water, H 20 Polar Molecule Polar = there is a distinct ‘pole’ on both ends of the molecule, one positive, the other negative. This happens when the molecule is asymmetrical.

Ionic Vs. Covalent �Ionic Bonding �Gain or Lose Electrons �Metal Combined with a nonmetal. �Compound �Covalent Bonding �Sharing Electrons �Nonmetals with nonmetals �Molecule � Polar or Non-Polar