Elements, Compounds, Mixtures SUMMARY

Elements, Compounds, and Mixtures

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• Elements 1.1
• Compounds 1.2
• A closer look at atoms
• Elements Compounds and Mixtures Quiz
• Bildunterschrift: The Atom theory of Matter

Elements

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• Bildunterschrift: Elements can be classified as metallic and non-metallic
• Elements are substances that are made up of just one type of atom. Each element has a unique set of characteristics that scientists refer to as its properties. Elements can be classified into metallic and non-metallic elements. All metallic elements -:
• shiny
• solid at room temperatures(apart from mercury)
• good conductors of heat and electricity
• malleable(bent and hammered into sheets)
• ductile(stretched into wires
• Non -metallic elements-:
• dull(not shiny)
• do not conduct heat or electricity)
• Break or crumble when you bend them(brittle)
• solid or gases at room temperature(apart from bromine)
• There are 118 elements, but only 91(92) occur naturally.

Atoms in Elements

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• Bildunterschrift: Atoms can exist as: Monatomic, Molecular and Lattice
• The way atoms are arranged in Elements determines many of the physical properties of an element. Monatomic elemets are rare, with only 6 of the 92 naturally occurring elements being monatomic. These are -: Helium, Neon, Argon, Krypton, Xenon and Radon.
• Molecules are cluster of two or more atoms bonded together. In a molecular element, all the molecules are identical with the same shape, size, number and types of atoms.
• The atoms in metals don't form molecules, but instead form large grid-like structures known as crystal lattices. In metal lattices, the atoms are only weakly joined to each other. As a result, metals can be bent into wires.
• In non-metallic lattices, the atoms are strongly bonded to each other. This makes them hard and brittle.

The many faces of Carbon

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• Bildunterschrift: Allotropes of Carbon
• Charcoal: Carbon in the form of charcoal is used for drawing because it's black and soft and crumbles easily.
• Graphite: The carbon atoms in graphite form layers. The layers are difficult to break but can slide over each other easily. This makes graphite an excellent lubricant.
• Diamond: Carbon in the form of diamond is the hardest natural substance on Earth because the bonds between the atoms are extremely strong.
• Carbon Fibre: Carbon fibre is very light , very strong and flexible and so is often used in sporting equipment such as the mountain bike.
• Nanotubes: A carbon nanotube can be thought of as a sheet of carbon rolled into a tube. These tubes are very tough so scientists are researching how to spin then into yarn to create new-age materials.

END OF ELEMENTS

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• https://www.youtube.com/watch?v=NzJPRhymoY0 (Einbetten)
• Bildunterschrift: Periodic Table
• Bildunterschrift: Atoms and elements video

Compounds

• Compounds are made up of more than one type of atom. Compounds have properties that are usually very different from the properties of elements.
• Each molecule is made by combining different numbers of the same elements, oxygen hydrogen etc. Scientists represent the molecules of compounds in a similar way to the molecules of an element. H2O indicates that there are 2 hydrogen atoms for every oxygen atom.
• Compounds can also form crystal lattices. In these lattices, the atoms are strongly bonded to each other so they tend to be very hard solids at room temperatures. In a lattice of sodium chloride, sodium and chloride atoms form a grid-like structure with one sodium atom for every chlorine atom.