Thursday, June 28, 2012
Alloys
Alloys are an example of a mixture. An alloy is a mixture of metals with other elements.Alloys are used more frequently than metals because they are stronger.
Mixtures
Mixtures are formed when two substances are added together without chemical bonds being formed.
Examples: muddy water and air
Mixtures can be made up of elements and compounds.
Examples: muddy water and air
Mixtures can be made up of elements and compounds.
Compounds
A compound is a pure substance that contains two or more elements chemically combined.
The compound that contains two or more elements ends with an -ide.
magnesium + oxygen -> magnesium oxide
When the elements are chemically combined, there is always a fixed ratio.
Example: the ratio to hydrogen atoms to oxygen atoms in water is always 2 :1.
The smallest part of a compound is a molecule. Depending on the compound, the smallest particle can also be called the formula unit.
A compound can be represented by a chemical formula.
Heat can be used to form compounds. Heat can also be used to break down compounds into elements or simpler compounds. Electricity can also be used to break down compounds.
The compound that contains two or more elements ends with an -ide.
magnesium + oxygen -> magnesium oxide
When the elements are chemically combined, there is always a fixed ratio.
Example: the ratio to hydrogen atoms to oxygen atoms in water is always 2 :1.
The smallest part of a compound is a molecule. Depending on the compound, the smallest particle can also be called the formula unit.
A compound can be represented by a chemical formula.
Heat can be used to form compounds. Heat can also be used to break down compounds into elements or simpler compounds. Electricity can also be used to break down compounds.
Monday, June 25, 2012
Iodine
1. Metallic, non-metallic or metalloid?
Ans: Non-metallic
2. Appearance
Solid: Bluish-black. Vapor: Purple
3. Physical properties
Boiling point: 184 degrees celsius
Melting point: 113.5 degrees celsius
Conductor of electricity: Poor conductor of electricity
Conductor of heat: Poor conductor of heat
Hardness/brittle/malleable/ductile: Not too sure, malleable?
4. Uses and occurrence
Iodine is needed by our body for metabolism in our cells. Iodine is also required for the thyroid glands to function normally.
Sources:
http://www.chemicool.com/elements/iodine.html
http://www.livestrong.com/article/501359-characteristics-of-iodine/
Ans: Non-metallic
2. Appearance
Solid: Bluish-black. Vapor: Purple
3. Physical properties
Boiling point: 184 degrees celsius
Melting point: 113.5 degrees celsius
Conductor of electricity: Poor conductor of electricity
Conductor of heat: Poor conductor of heat
Hardness/brittle/malleable/ductile: Not too sure, malleable?
4. Uses and occurrence
Iodine is needed by our body for metabolism in our cells. Iodine is also required for the thyroid glands to function normally.
Sources:
http://www.chemicool.com/elements/iodine.html
http://www.livestrong.com/article/501359-characteristics-of-iodine/
Elements
Notes I picked out:
Different elements are represented by different chemical symbols
Elements are pure substances that cannot be broken down into two or more simpler substances by chemical processes or electricity.
Examples: copper
Water is not an element because it can broken down by electricity into hydrogen and oxygen.
Elements can be classified into two major groups: Metal and Non-metal
Metals exist as atoms in a giant structure and most non-metals exist as molecules
Elements that have both properties of metals and non-metals are called metalloids.
Example: silicon
Elements are made up of tiny particles called atoms.
Elements that do not exist as atoms are called monatomic elements. Their atoms are not joined together chemically.
A molecule is a group of two or more atoms that are chemically combined. The molecular formula of an element is the chemical symbols plus the number of atoms needed when a molecule of that element is formed.
Molecules formed by the combination of two atoms are called diatomic molecules. Molecules that consist of three atoms are called triatomic molecules. Molecules that are formed by four or more aims are called polyatomic molecules.
Different elements are represented by different chemical symbols
Elements are pure substances that cannot be broken down into two or more simpler substances by chemical processes or electricity.
Examples: copper
Water is not an element because it can broken down by electricity into hydrogen and oxygen.
Elements can be classified into two major groups: Metal and Non-metal
Metals exist as atoms in a giant structure and most non-metals exist as molecules
Elements that have both properties of metals and non-metals are called metalloids.
Example: silicon
Elements are made up of tiny particles called atoms.
Elements that do not exist as atoms are called monatomic elements. Their atoms are not joined together chemically.
A molecule is a group of two or more atoms that are chemically combined. The molecular formula of an element is the chemical symbols plus the number of atoms needed when a molecule of that element is formed.
Molecules formed by the combination of two atoms are called diatomic molecules. Molecules that consist of three atoms are called triatomic molecules. Molecules that are formed by four or more aims are called polyatomic molecules.
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