Chapter 2

• What are the three types of bonding between atoms?

  Ionic, covalent and metallic
• When does ionic bonding occur?


  When a metal reacts with a non-metal
• Why do Group 0 (noble gas) elements NOT react?

  They already have a full outer shell
• How does an ionic bond form?


  The metal atoms transfers electrons to the non-metal atom
• When Group 1 metals react, what charge do their ions have?

  1+
• When Group 2 metals react, what charge do their ions have?

  2+
• When Group 7 non-metals react, what charge do their ions have?

  1-
• When Group 6 non-metals react, what charge do their ions have?

  2-
• What structure does an ionic compound have?

  Giant structure of ions
• What holds an ionic compound together?


  The strong electrostatic forces of attraction acting between positive and negative ions
• What are the limitations of using a two-dimensional model to represent a giant ionic structure?

  A two-dimensional space-filling model does not show how the next layer of ions is arranged
• What are the limitations of using a three-dimensional ball and stick model to represent a giant ionic structure?


  Using sticks for bonds is misleading because the forces of attraction between ions actually act in all directions
• How do atoms form covalent bonds?

  By sharing pairs of electrons
• Describe the strength of a covalent bond

  Strong
• What is the chemical formula of hydrogen?

  H2
• What is the chemical formula of nitrogen?


  N2
• What is the chemical formula of hydrogen chloride?

  HCl
• How do you know from the formula of a substance that it is covalently bonded?

  The elements in the molecule are all non-metal elements
• Give two examples of covalently bonded substances that has giant covalent structures

  Diamond and silicon dioxide
• What are the limitations of using a three-dimensional ball and stick model to represent molecules or giant structures?

  A three-dimensional ball and stick model does not show the true shape of the molecule
• What is the structure of a metal?

  A metal is a giant structure of atoms arranged in a regular pattern
• Why are metallic bonds strong?

  The sharing of delocalised electrons give rise to strong bonds
• What are the three states of matter?

  Solid, liquid, gas
• Describe the arrangement and movement of particles in a gas

  Particles are far apart, randomly arranged, move quickly in all directions and have the highest energy
• Describe the properties of a solid

  Solids have a fixed shape, cannot flow and cannot be compressed
• Describe the properties of a solid

  Gases flow and completely fill their container, and can be compressed
• What happens at the melting point of a substance?

  Melting and freezing takes place
• What happens at the boiling point of a substance?

  Boiling and condensing takes place
• What does the amount of energy needed to change state depend upon?

  The strength of the forces between particles
• At the strength of the forces between particles in a substance increase what happens to the melting and boiling points?

  They get higher
• What are the limitations of the particle diagrams used to represent solids, liquids and gases?

  The particle diagram assumes no forces between particles when there are, assumes the particles are solid spheres when atoms are mostly empty space and not spherical
• In terms of energy change and bonding what happens when solids melt?

  Particles gain energy and some bonds are broken
• What state of matter are substances that consist of small molecules usually?

  Liquids and gases
• Why do small molecules have relatively low melting and boiling points?

  There are only weak forces between molecules (intermolecular forces) and it is only these forces, not the covalent bonds, that are overcome when the substance melts or boils
• Describe the intermolecular forces between polymer molecules

  Relatively strong
• What state of matter are giant covalent structures?

  Solids
• Explain the very high melting and boiling points of giant covalent structures

  To melt or boil the strong covalent bonds must be overcome so a large amount of energy is required
• Why can metals be bent or shaped?

  Because the layers of atoms can slide over each other
• Why are pure metals soft?

  Because the layers of atoms can slide over each other
• Why are alloys harder than pure metals?

  In alloys, the atoms are different sizes so the smaller or bigger atoms distort the layers of atoms in the pure metals making it harder for the layers to slide over each other