Chemistry bonding

• Exothermic reaction

  Releases heat. The energy required to break bonds in the reactant is exceeded by the energy released when chemical bonds are formed in the product
• what is a metal

  Metallic solid made up of positively charged metal nuclei in a lattice arrangement, surrounded by a 'sea' of delocalised valence electrons
• Endothermic reaction


  Absorbs energy from its surroundings
• how can a metal be a conductive substance

  • Electrical conductor due to delocalised valence electrons able to move freely through the lattice structure
• bonding for a metal

  Negatively charged valence electron attracted to the positive charge of nearby nuclei
• ionic substance are made of?

  Made up of positively charged cations and negatively charged anions held together in a regular lattice structure by strong electrostatic forces of attraction
• When a solid is melted or dissolved in water


  Ions are freed from their fixed positions and become free to carry an electrical current
• Malleable metals like silver

  Can be forced into different shapes due to the type of bonding they have. Positively charged nuclei can change position and still experience strong non-directional electrostatic attraction to nearby delocalised valence electrons
• Ionic bonding

  Consists of alternating positively charged cations and negatively charged anions held together by strong electrostatic forces of attraction in a regular 3D lattice structure, making it a very hard substance
• how can a substance be polar

  Due to asymmetrical bonds, the molecule is polar with the atom With the highest electrons being the most electronegative
• Ionic bonding


  When a metal reacts with non-metal, the metal loses one valence electron and that electron is gained by the non-metal atom. The cation and anion are held together by strong electronic forces of attraction
• Solubility of a polar substances 


  Dissolves in water, a polar solvent, due to the force of attraction between solvent molecules and ions being greater than the force between the ions themselves
• Melting point of MgCl2 is explained by the strong electronic forces of attraction in the regular lattice structure, requiring a lot of heat to overcome and allow the solid to become a liquid
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  How can a polar substance dissolve in water (Solubility)

  The negatively charged ends of the water molecule attract the positively charged cations of the polar substance. The polar charged ends of the water molecules are attract the negatively charged anions of the polar substance, pulling it apart.
• What do the newly freed ions become

  Free to to carry an electrical currant
• What is required to break these strong electrostatic forces of attraction when a metal is melting

  High heat to overcome the bonds, this causes the ions to move around each other (liquid)
• Describe the endothermic process of an ionic solid dissolving in water. 


  a ionic substance contains strong electrostatic forces of attraction, when it is dissolved energy is absorbed in breaking these bonds.
• Creating or strengthening bonds is a what? Reaction give a example

  Exothermic reaction, a solid melting.
• Describe the conductivity of metals 


  Metals are made up of positively charged metal nuclei in a lattice arrangement, surrounded by a ‘sea’ of delocalised valence electrons. They are held together by negatively charged valence electron being attracted to the positively charged nuclei,

  It becomes an electrical conductor because the delocalised electrons are able to move freely through the lattice structure.