metals and their uses

• Different properties of metals:

  -Sonorous: able to produce a deep sound

  -Strong tensile strength due to strong bonds.

  -High-density: large amount of particles packed to small spaces

  -Malleable: does not break when changing shape as the atoms slide over each other.

  -Ductile: can be stretched and formed like wires

  -Shiny: reflects light when polished.
• Different properties of metals:

  -Melting and boiling points: requires a large about of energy to break bonds.

  -Magnetic: alloys with metals allow them to attract magnetic materials
• Different properties of metals:

  -Energy and electricity conductor: particles are closely packed, therefore vibration is passed on quickly.

  -Electric currents flow through the metal and wamrs the cooler parts of the metal.
• Metals can also have chemical properties:

  -Reaction with oxygen (oxidation)

  -Reaction with water

  -Reaction with acids.
• They can also react with halogens and other non-metals. When they react, they form a single solid compound.
• Metals can be catalysts:

  -changes the speed of the reactions without being permanently changed itself.
• Catalysts: substances that cause a chemical reaction to proceed more quickly without being used up.
• Catalytic converters:

  -Includes oxidation and reduction.

  STEPS:

  1. Exhaust gases like carbon monoxide, nitrogen oxides, and unburned hydrocarbons are introduced.
  2. Oxidation catalyst: oxidation from carbon monoxide to carbon dioxide and unburned hydrocarbons to carbon dioxide and water (2CO + O2 ---> N2 + 2CO2)
  3. Reduction catalyst: reduction of nitrogen oxides into nitrogen gas and oxygen.
  4. Pollutants from exhaust gases are now less harmful substances.
• Physical properties of metals:

  -can be observed or measured

  -influenced by molecular structure of atoms

  Chemical properties of metals:

  -influenced by how metals bond with other elements

  -Describe ability to react with other substances to produce a new product.
• Corrosion is when a metal reacts with oxygen (oxidation). The formula is:

  metal + oxygen --> metal oxide.

  When a metal oxide forms, the metal corrodes.
• Rust: corrosion of iron by oxygen and water.
• Oxygen and water both must be present in order for iron to rust.
• Rust can weaken and destroy fractures, therefore having a barrier like paint is important to keep the air and water away from metal.
• Metals with water = metal + water --> metal hydroxide + hydrogen.
• Cu + H2O --> Cu(OH)2 + H2.
• Ti + O2 --> TiO
• The Reactivity Series states: PLEASE STOP CALLING ME A CARELESS ZEBRA, INSTEAD TRY LEARNING HOW COPPER SAVES GOLD.
• Metal + acid --> Metal salt + hydrogen
• The test for hydrogen is a lit splint, if it burns with a squeaky pop it is hydrogen.
• The test for hydroxide is mainly through their reactions, like adding to an indicator solution like litmus. If the hydroxide ions are present, then there is hydroxide present, and the color can change according to the pH level.
• Difference between metal oxide and non-metal oxide:

  Metal oxide:

  -basic

  -forms basic solutions in water

  Non-metal oxide:

  -Acidic

  -Form acidic solutions in water.
• Examples of acids:

  -Hydrochloric acid (HCl)

  -Sulphuric Acid (H2 SO4)

  -Nitric Acid (HNO3)
• How to test the acidity of rainwater:

  -Add an indicator (colour will change according to pH level)

  -Litmus test (red if acidic)

  -pH meter (below 7 is acidic)
• When a metal reacts with acid, effervescence occurs and metal seems to disappear in the solution. The gas is hydrogen, but a salt seems invisible as they are colourless and soluble. We can only see the salt when it is evaporated.
• Alloys are mixtures of metals with other elements to add more desirable properties to the metal.
• When a pure substance is heated, it can reach to its melting point and become a liquid. This continues to rise until the boiling point, where evaporation occurs throughout the liquid.
• The melting points and boiling points of liquids are all fixed and occur in precise temperatures, which helps them to identify substances.
• The melting and boiling points of alloys depends on the percentage of the different metals in the alloy.
• Alloys can change physical and chemical properties.
• In alloys, atoms block the structure of atoms in the original metal so they cannot slide easily.