2 8.1 Forming Chemical Bonds The force that holds two atoms together is called a chemical bond.There are three types of bonds:Ionic bonds (Metal/Nonmetal)Covalent bonds (Nonmetal/Nonmetal)Metallic bonds (Metal/Metal)
3 8.2 The Formation and Nature of Ionic Bonds Cations are atoms with a positive charge.Anions are atoms with a negative charge.The electrostatic force holds ions of opposite charge together, forming an ionic bond.
4 Characteristics of covalent bonds: Formed between nonmetal pairsElectrons are shared between atomsLow melting pointsDo not conduct electricityBrittle solids
5 Properties of metallic bonds: - This type of bonds do not share electrons nor lose electrons.Delocalized electrons- meaning the electrons overlapProperties of metals are determined by the number of valence electrons.
6 Predict if the following bonds are ionic or covalent: a) C-Nb) N-Oc) Na-Fd) Mg-Se) C-Hf) Ca-F
8 Standard 22.b- Students know chemical bonds between atoms in molecules such as H2, CH4, H2CCH2, N2, Cl2 and many large biological molecules are covalent.Out of these elements listed above which are covalent?
9 2.c- Students know salt crystals, such as NaCl, are repeating patterns of positive and negative ions held together by electrostatic attraction.
10 2.d Students know the atoms and molecules in liquids move in a random pattern relative to one another because the intermolecular forces are too weak to hold the atoms or molecules in a solid form.
11 8.3 Names and Formulas for Ionic Compounds The simplest ratio of the ions represented in an ionic compound is called a formula unit.