atoms and elements

Vivek Bheeroo - FORM 2I - LBISVivek Bheeroo - FORM 2I - LBIS

In this presentation, you will learn more about:In this presentation, you will learn more about:-Atoms-Atoms

-Elements-Elements-Compounds-Compounds

-Symbols-Symbols-Properties of elements-Properties of elements

-The periodic table-The periodic table-Molecules-Molecules-Formulae-Formulae

-Chemical reaction-Chemical reaction-Word equation-Word equation


Everything around us is made up of Everything around us is made up of particlesparticles. . These particles are known as These particles are known as atomsatoms and are so and are so small that they can only be seen with a powerful small that they can only be seen with a powerful microscope. There are about 100 different types microscope. There are about 100 different types of atoms for example: Oxygen, Hydrogen, Gold, of atoms for example: Oxygen, Hydrogen, Gold, Platinum, Scandium and Sulfur atoms. Each Platinum, Scandium and Sulfur atoms. Each type of atom is an type of atom is an elementelement. Some objects are . Some objects are composed of only one element. Some objects composed of only one element. Some objects also contain more than one element. These also contain more than one element. These objects contain two or more elements joined objects contain two or more elements joined together. The object is then known as a together. The object is then known as a compoundcompound..


Scientists around the Scientists around the world use a common world use a common set of set of symbolssymbols to to represent all the represent all the different elements. In different elements. In some cases the some cases the symbol of the element symbol of the element is the first letter of the is the first letter of the name of the element. name of the element. It is written in capital.It is written in capital.

SymbolSymbol ElementElement

HH hydrogenhydrogen

FF fluorinefluorine

II iodineiodine

BB boronboron

SS sulfursulfur

OO oxygenoxygen


Several elements begin with Several elements begin with the same letter for example the same letter for example Scandium and Silicon. To Scandium and Silicon. To identify any of these as a identify any of these as a separate element, its symbol separate element, its symbol has the first letter of the name has the first letter of the name followed by the second letter followed by the second letter from within the name. from within the name. Scandium has the symbol Sc, Scandium has the symbol Sc, while silicon has the symbol Si. while silicon has the symbol Si. T he first letter is always a T he first letter is always a capital one and the second capital one and the second letter is in lower case.letter is in lower case.

ElementElement SymbolSymbolmagnesiummagnesium MgMg

manganesemanganese MnMn

chlorinechlorine ClCl

calciumcalcium CaCa

berylliumberyllium BeBe

brominebromine BrBr


Sometimes the Sometimes the symbol for an element symbol for an element is derived from the is derived from the Latin name for that Latin name for that element.element.

ElementElement SymbolsSymbols

SodiumSodium NaNa( natrium( natrium))

LeadLead PbPb( plumbum)( plumbum)

IronIron FeFe( ferrum)( ferrum)

PotassiumPotassium KK( kalium)( kalium)


Different elements can have very different Different elements can have very different propertiesproperties. Some are . Some are solidssolids, some are , some are liquidsliquids and some are and some are gasesgases.. Some are Some are essential to our health and well being, but essential to our health and well being, but some are highly toxic. Early scientists some are highly toxic. Early scientists examined the elements that had been examined the elements that had been discovered and tried find links and discovered and tried find links and patterns between them. patterns between them.


The The periodic tableperiodic table was invented by was invented by Dimitri Dimitri MendeleevMendeleev. He used the properties of . He used the properties of each element to decide where to place each element to decide where to place them in his table. On the left and middle them in his table. On the left and middle part of the table, there are the metal part of the table, there are the metal elements and on the left part of the table, elements and on the left part of the table, there are the non- metal elements.there are the non- metal elements.

Dimitri Iwanowitsch Mendeleev


We have seen that when the atoms of two or We have seen that when the atoms of two or more elements are joined together they form a more elements are joined together they form a compound. Water is a compound because it compound. Water is a compound because it contains atoms of two different elements, contains atoms of two different elements, hydrogen and oxygen. When hydrogen and hydrogen and oxygen. When hydrogen and oxygen join together to make this compound, the oxygen join together to make this compound, the water has completely different properties of water has completely different properties of either hydrogen or oxygen. When the two either hydrogen or oxygen. When the two elements join together, they are arranged in a elements join together, they are arranged in a particular way. It consists of two hydrogen atoms particular way. It consists of two hydrogen atoms joined to one oxygen atom. This is then called a joined to one oxygen atom. This is then called a moleculemolecule..

A water molecule


The compound we call water has the The compound we call water has the formulaformula HH22OO. This is a shorthand way of . This is a shorthand way of saying that every water molecule consists saying that every water molecule consists of two hydrogen atoms and one oxygen of two hydrogen atoms and one oxygen atom. The gas we call oxygen has the atom. The gas we call oxygen has the formula formula OO2.2. This means that an oxygen This means that an oxygen molecule consists of two oxygen atoms molecule consists of two oxygen atoms joined together.joined together.

Oxygen molecule


New compounds are made when atoms of New compounds are made when atoms of elements are joined together during elements are joined together during chemical reactionschemical reactions. These new . These new compounds can have very different compounds can have very different properties from the elements that formed properties from the elements that formed them. We can describe chemical reactions them. We can describe chemical reactions that make new compounds using that make new compounds using word word equations.equations.


When a balloon of hydrogen explodes, we are When a balloon of hydrogen explodes, we are seeing and hearing a very vigorous chemical seeing and hearing a very vigorous chemical reaction between the hydrogen in the balloon reaction between the hydrogen in the balloon and oxygen in the air. We describe this reaction and oxygen in the air. We describe this reaction with the following word equation.with the following word equation.

Hydrogen + oxygen Water


The metal sodium reacts with chlorine to The metal sodium reacts with chlorine to produce the compound produce the compound sodium chloridesodium chloride..

Sodium + chlorideSodium + chloride sodium chloridesodium chloride


When a slice of toast is overcooked, the When a slice of toast is overcooked, the surfaces become covered with black surfaces become covered with black carbon. This carbon may react with the carbon. This carbon may react with the oxygen in the air to form the gas oxygen in the air to form the gas carbon carbon dioxide.dioxide.

Carbon + oxygen carbon dioxide


When heated, the metal copper reacts When heated, the metal copper reacts with the non- metal sulfur to produce the with the non- metal sulfur to produce the compound compound copper sulfidecopper sulfide..

Copper sulfide

Copper + sulfur copper sulfide


ReferencesReferences

BooksBooks Brian Arnold, Geoff Jones, Mary Jones, Emma Poole. Absolute Science: Brian Arnold, Geoff Jones, Mary Jones, Emma Poole. Absolute Science:

Pupil Book 2, 2003.Pupil Book 2, 2003. Martin Sherwood, Wendy Allen, Nigel Davis, Mick Gillah. Chemistry Today: Martin Sherwood, Wendy Allen, Nigel Davis, Mick Gillah. Chemistry Today:

The World Book Encyclopedia of Science, 1989.The World Book Encyclopedia of Science, 1989. Ministry of Education and Scientific Research; Editions de L’Ocean Indien: Ministry of Education and Scientific Research; Editions de L’Ocean Indien:

Form 3, 2005.Form 3, 2005. Tony Eugene, Ellis D. Miner. Discover Stars & Planets; Publications Tony Eugene, Ellis D. Miner. Discover Stars & Planets; Publications

International Ltd, 2003.International Ltd, 2003. Chancellor Press. Tell me Why? Octopus Publishing Group Ltd, 2001.Chancellor Press. Tell me Why? Octopus Publishing Group Ltd, 2001.

Internet(Yahoo)Internet(Yahoo) Atoms and ElementsAtoms and Elements users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/ElementsElements.html.html www.karentimberlake.com/www.karentimberlake.com/atomsandatomsand.htm.htm www.chem4kids.com/files/elem_intro.htmlwww.chem4kids.com/files/elem_intro.html hyperphysics.phy-astr.gsu.edu/hbase/chemical/atom.htmlhyperphysics.phy-astr.gsu.edu/hbase/chemical/atom.html www.pslc.ws/macrog/kidsmac/www.pslc.ws/macrog/kidsmac/atomsatoms.htm.htm www.colorado.edu/physics/2000/www.colorado.edu/physics/2000/elementselements_as__as_atomsatoms/index.html/index.html www.stwww.standandards.dfes.gov.uk/schemes2/secondary_science/sci08e/?viewards.dfes.gov.uk/schemes2/secondary_science/sci08e/?view

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