1.can anyone identify the difference between elements, compounds and mixtures in terms of particle theory.
An element is a pure substance which cannot be decomposed into simpler substances.
A compound is a pure substance which can be decomposed into simpler substances. For example, NaCl----->Na+Cl
A mixture can be seperated into two or more pure substances by physical or mechanical means such as filtering, boiling or using a magnet or tweezers.
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2. describe the phyiscal properties used to classify compounds as ionic or covalent molecular or covalent network.
Ionic (a metal and a non-metal)
1) High melting and boiling points.
2) Conducts electricity only in molten or dissolved form.
3) Hard and brittle.
4) Electrostatic forces holds the particles together in the solid.
Chemical examples:
NaCl, CuSO4, (NH4)2SO4, Ca(OH)2, FeCl.
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Covalent
1) High melting and boiling points.
2) on electrical conductivity.
3) Hard and brittle
4) Covalent bonding throughout the crystal
Chemical example:
Sio, Diamond
NOTE: Graphite is covalent but it conducts electricity.
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3. describe using diagrams ionic compounds in terms of repeating three-dimensional lattices of ions.
When sodium is burned in a chlorine atmosphere, it produces the compound sodium chloride. This has a high melting point (800 ºC) and dissolves in water to to give a conducting solution therefore sodium chloride is an ionic compound.
Electrostatic attraction are in these oppositely charged ions packing together in a lattice. The attractive forces holding the ions in place can be referred to as ionic bonds. (i think thats what you're asking for)
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Hope i helped