CHEMICAL BONDING

Compounds- when elements combine in fixed ratios

Chemical bonds- what hold compounds together

3 TYPES OF CHEMICAL BONDING

• Metallic- between 2 metals

  • Metal atom arrangement

    • Electron sea model- model used to describe solid metals

      • Valence electrons are freely flowing; they arent associated with a single atom and are instead shared within the metal cations

      • the metal is held together by the strong attraction between the cations and electrons. This is metallic bonding

  • Properties of metals (prove how metallic bonding is strong)

    • High melting point- the temperature where the metal goes from solid to liquid

      • Liquids are less compact than solids, therefore if the melting point is high, the bond must be strong too since the atoms wouldnt move apart (like how you need for it to be a liquid)

    • Malleability- ability of an object to be shaped into sheets without breaking

      • the metal is deformed, but the free flow of electrons keep the positive atoms from repelling each other

        

    • Ductility- ability of an object ot be shaped into wires or rods without breaking

      • has the same mechanics as malleability, the ‘sea’ of electrons keep the positive atoms from repelling each other, which means it will break

    • Conductivity- ability for heat/electricity to pass through

      • the mobile sea of electrons help in the distribution of heat and electricity, since they are constantly moving

    • Luster- ability to reflect light, giving a shiny appearance

      • the mobile electrons absorb light and immediately re-emit it

      • 

• Ionic- between a metal and a nonmetal

  • Ions- atoms or groups of atoms that are electrically charged

    • Cations- positively charged

    • Anions- negatively charged (a n=negative)

    • 

      THIS MEANS: metals tend to be negatively charged while nonmetals tend to be positively charged, opposite charges attract each other

  • Properties of ionic compounds

    • Crystalline- ionic compounds create crystal-like lattice structures (imagine salt)

      • these crystals form because of the alternating positive and negative ions

    • Hard and brittle- this means that the structure is solid but it is easily crushed

      

      • the crystal is arranged in alternating positive and negative ions, when an external force presses on it, it moves, displacing the alternating ions. when this happens, positive ions and negative ions will be next to each other, causing them to repel each other (break)

    • High melting and boiling points- you need high temperatures to seperate the compound

      • it is similar to metallic compounds in this way, the bond between metals and non-metals cant be easily seperated through temperature.

    • Conducts electricity- ionic compounds can conduct electricity when it is dissolved in water

      • this is because you partially expose the metal part of the compound, and the ions can also move around more easily. this makes it easier to conduct electricity (the same for heat)

  • Octet rule

    • atoms like having a full shell (8 valence electrons) like noble gases. to achieve this in a compound, they borrow each others’ electrons

      • 5 and up: tend gain electrons

      • 4 and down: tend to lose electrons

  • Valence electrons

    • Valence electrons are electrons on the outermost orbit/ring of the atom

  • Shielding electrons

    • Shielding electrons are electrons in the inner orbit/ring of the atom

  • Lewis structure

    • This is how you represent the valence electrons in an atom (represented by dots)

  • Ionic bonds

    • attraction lies in the 2 oppositely charged atoms (which is what bond the compound together)

Covalent- between 2 non-metals

HOW TO WRITE LEWIS STRUCTURE

1. First start off with the 4 outer circles in a clockwise motion

2. Once you complete those 4, you go back again

   • you can do this in any order

   • always write the metal first

EXPLANATIONS FOR WRITTEN EXAMPLES: