Elements, compounds and mixtures. Elements Elements cannot be broken down into anything simpler by...
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Transcript of Elements, compounds and mixtures. Elements Elements cannot be broken down into anything simpler by...
![Page 1: Elements, compounds and mixtures. Elements Elements cannot be broken down into anything simpler by either chemical or physical means. The smallest part.](https://reader036.fdocuments.us/reader036/viewer/2022062301/5697c02e1a28abf838cda05c/html5/thumbnails/1.jpg)
Elements, compounds and mixtures
![Page 2: Elements, compounds and mixtures. Elements Elements cannot be broken down into anything simpler by either chemical or physical means. The smallest part.](https://reader036.fdocuments.us/reader036/viewer/2022062301/5697c02e1a28abf838cda05c/html5/thumbnails/2.jpg)
Elements
• Elements cannot be broken down into anything simpler by either chemical or physical means.
• The smallest part of an element is the atom.
• Atoms of each element are identical but different from those of all other elements.
![Page 3: Elements, compounds and mixtures. Elements Elements cannot be broken down into anything simpler by either chemical or physical means. The smallest part.](https://reader036.fdocuments.us/reader036/viewer/2022062301/5697c02e1a28abf838cda05c/html5/thumbnails/3.jpg)
Eg; Sulphur only contains one type of atom, S.
Iron filings only contain one type of atom, Fe.
![Page 4: Elements, compounds and mixtures. Elements Elements cannot be broken down into anything simpler by either chemical or physical means. The smallest part.](https://reader036.fdocuments.us/reader036/viewer/2022062301/5697c02e1a28abf838cda05c/html5/thumbnails/4.jpg)
Compounds
• Compounds consist of two or more particles joined together by chemical bonds.
• When elements react to form compounds they give, take or share electrons to form chemical bonds.
• Their particles can only be separated by breaking the chemical bonds by carrying out a chemical reaction.
![Page 5: Elements, compounds and mixtures. Elements Elements cannot be broken down into anything simpler by either chemical or physical means. The smallest part.](https://reader036.fdocuments.us/reader036/viewer/2022062301/5697c02e1a28abf838cda05c/html5/thumbnails/5.jpg)
Eg; Salt, NaCl, consists of sodium atoms chemically combined with chlorine atoms.
The composition of a compound is constant. Salt always has one ion of sodium combined with one ion of chlorine.
![Page 6: Elements, compounds and mixtures. Elements Elements cannot be broken down into anything simpler by either chemical or physical means. The smallest part.](https://reader036.fdocuments.us/reader036/viewer/2022062301/5697c02e1a28abf838cda05c/html5/thumbnails/6.jpg)
Molecules
Molecules consist of two or more atoms joined together by a chemical bond.
The atoms may be the same eg Oxygen.
Or they may be different eg carbon dioxide.
Two atoms of oxygen joined by a chemical bond.
One atom of carbon joined by chemical bonds to two atoms of oxygen.
![Page 7: Elements, compounds and mixtures. Elements Elements cannot be broken down into anything simpler by either chemical or physical means. The smallest part.](https://reader036.fdocuments.us/reader036/viewer/2022062301/5697c02e1a28abf838cda05c/html5/thumbnails/7.jpg)
Diatomic molecules
Molecules that consist of two atoms are known as diatomic.
Many gases are diatomic.
Oxygen Hydrogen
Nitrogen Chlorine
![Page 8: Elements, compounds and mixtures. Elements Elements cannot be broken down into anything simpler by either chemical or physical means. The smallest part.](https://reader036.fdocuments.us/reader036/viewer/2022062301/5697c02e1a28abf838cda05c/html5/thumbnails/8.jpg)
Mixtures
• Mixtures are made up of particles that have been physically mixed together, but are not linked in any way.
• Mixtures have a variable composition.• Their different components can be easily
separated by physical methods.• Mixtures can be made up of elements and/or
compounds.• Eg; Air is a mixture of gases, mainly nitrogen
(N2) and oxygen (O2).
![Page 9: Elements, compounds and mixtures. Elements Elements cannot be broken down into anything simpler by either chemical or physical means. The smallest part.](https://reader036.fdocuments.us/reader036/viewer/2022062301/5697c02e1a28abf838cda05c/html5/thumbnails/9.jpg)
Sulphur and iron filings can be physically added together to form a mixture.
![Page 10: Elements, compounds and mixtures. Elements Elements cannot be broken down into anything simpler by either chemical or physical means. The smallest part.](https://reader036.fdocuments.us/reader036/viewer/2022062301/5697c02e1a28abf838cda05c/html5/thumbnails/10.jpg)
Eg; Sand (SiO2) and salt can be combined to make a mixture.
![Page 11: Elements, compounds and mixtures. Elements Elements cannot be broken down into anything simpler by either chemical or physical means. The smallest part.](https://reader036.fdocuments.us/reader036/viewer/2022062301/5697c02e1a28abf838cda05c/html5/thumbnails/11.jpg)
Air is a mixture of gases
![Page 12: Elements, compounds and mixtures. Elements Elements cannot be broken down into anything simpler by either chemical or physical means. The smallest part.](https://reader036.fdocuments.us/reader036/viewer/2022062301/5697c02e1a28abf838cda05c/html5/thumbnails/12.jpg)
Separating mixtures Mixtures can be separated into their components using physical means.
Eg; A mixture of sulphur and iron filings can be separated using a magnet.
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Salt can be separated from sand by adding water, filtering and evaporating.
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Mixtures of liquids can be separated using fractional
distillation.
The lowest boiling point liquid appears first.
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Chromatography
• Chromatography (“colour writing”) is used to separate coloured liquids.
• The mixture is “spotted” on to filter paper, then placed in contact with a solvent.
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• Different liquids are soluble to different extents in the solvent.
• So as the solvent passes up the filter paper it separates the components of the mixture.