For a material to be a good conductor, the electricity passed through it must be able to move the electrons; the more free electrons in a metal, the greater its conductivity.
Examples of metals are aluminium, copper, iron, tin, gold, lead, silver, titanium, uranium, and zinc. Well-known alloys include bronze and steel. When a wave of light hits the metal, the sea of electrons absorb the energy from the light, which makes them vibrate at the atomic level. So a metal's shine is really reflected light , thanks to the special composition of the electrons. Metals conduct electricity by allowing free electrons to move between the atoms. If there is less energy transfer between atoms, there is less conductivity.
Pure silver and copper provide the highest thermal conductivity, with aluminum less so. Non — metals are materials not holding the characteristics of metals, means they are not shiny, hard, fusible , malleable, ductile, etc.
Many materials like coal and Sulphur are very soft and dull in appearance. They break down into very fine thin powdery mass on tapping with the hammer.
One characteristic that can be used to identify pure metals is density. If you determine the density of a pure metal, you can determine what the metal is, as shown in the table below. Suppose that you determine that the ring has a density of According to the Mohs scale, talc, also known as soapstone , is the softest mineral; it is composed of a stack of weakly connected sheets that tend to slip apart under pressure.
Hence, going by the above explanation, the hardest alkaline earth metal is Beryllium Be. Gold is toxic if consumed regularly. The symptoms of gold poisoning are no different than other forms of metal poisoning. The primary difference between gold and uranium is that gold isn't very reactive and so it has virtually no contact toxicity.
There are three main types of metals ferrous metals, non ferrous metals and alloys. Ferrous metals are metals that consist mostly of iron and small amounts of other elements.
Ferrous metals are prone to rusting if exposed to moisture. Learn more. What makes materials hard and strong? Ask Question. Asked 7 years, 5 months ago. Active 7 years, 5 months ago. Viewed 9k times. Improve this question. Add a comment. Active Oldest Votes. Improve this answer. Rick Sanchez Rick Sanchez 4 4 bronze badges.
Sensebe Sensebe 5, 13 13 gold badges 50 50 silver badges 83 83 bronze badges. Danu Towne Springer C. Towne Springer 1, 1 1 gold badge 8 8 silver badges 11 11 bronze badges. The "free electron sea" allows metal atoms to move around even easier because they are, for all practical purposes, always charge neutral unlike in an ionic crystal.
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Related 0. There are actually two different ways of placing the third layer in a close packed structure, but that goes beyond the requirements of current A'level syllabuses. Some metals notably those in Group 1 of the Periodic Table are packed less efficiently, having only 8 touching neighbours.
These are 8-co-ordinated. The left hand diagram shows that no atoms are touching each other within a particular layer.
They are only touched by the atoms in the layers above and below. The right hand diagram shows the 8 atoms 4 above and 4 below touching the darker coloured one. It would be misleading to suppose that all the atoms in a piece of metal are arranged in a regular way. Any piece of metal is made up of a large number of "crystal grains", which are regions of regularity. At the grain boundaries atoms have become misaligned. Note: Within a crystal grain you get rather subtle irregularities known as dislocations.
It isn't important to know about these for UK A level Chemistry or equivalent purposes, although they turn out to be essential in discussing the workability of metals at a higher level.
I haven't included a description of them here because it is quite difficult to visualise how they work, and I don't want to add unnecessary complications.
Metals tend to have high melting and boiling points because of the strength of the metallic bond. The strength of the bond varies from metal to metal and depends on the number of electrons which each atom delocalises into the sea of electrons, and on the packing.
Group 1 metals like sodium and potassium have relatively low melting and boiling points mainly because each atom only has one electron to contribute to the bond - but there are other problems as well:. Group 1 elements are also inefficiently packed 8-co-ordinated , so that they aren't forming as many bonds as most metals. They have relatively large atoms meaning that the nuclei are some distance from the delocalised electrons which also weakens the bond.
Metals conduct electricity. The delocalised electrons are free to move throughout the structure in 3-dimensions. They can cross grain boundaries. Even though the pattern may be disrupted at the boundary, as long as atoms are touching each other, the metallic bond is still present.
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