classification of matter elements, compounds, mixtures

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  • Slide 1
  • Classification of Matter Elements, Compounds, Mixtures
  • Slide 2
  • Lesson Objective Physical and Chemical Changes. Elements Compounds Mixtures
  • Slide 3
  • Physical and Chemical Changes All reaction in Chemistry can be divided into two types of changes: Physical or Chemical. Physical Change: NO new substance is formed. These changes are easily reversible or temporary. An example is dissolving salt in water. Other examples of physical change include: melting, boiling, mixing 2 solids or liquids.
  • Slide 4
  • Chemical Change: A NEW substance is formed. These changes are irreversible or permanent. The new substance formed will have different properties compared to its original elements. (E.g. different melting and different chemical reactions from the original substance.) Physical and Chemical Changes
  • Slide 5
  • One can recognize a chemical change from 2 observations: The new substance has a different appearance, such as different color or different physical state. An example is the electrolysis of water. Reason: Electrolysis of water produces two new substances, Hydrogen gas and oxygen gas. Hydrogen and oxygen are both gases but water is a liquid. A lot of heat is given out in a chemical changes. Chemical changes are called chemical reactions. Physical and Chemical Changes
  • Slide 6
  • Illustration of chemical changes
  • Slide 7
  • An Overview
  • Slide 8
  • Elements, Compounds and Mixtures single, attached, play play
  • Slide 9
  • Introducing Little Miss Element Hi! I am Little Miss Element I am PURE SUBSTANCE I cannot be broken down into any simpler substance by means of a chemical reaction* or electricity**! *Chemical process refers to chemical reaction or heat **Electricity refers to electrolysis
  • Slide 10
  • Elements Definition of an element: An element is a pure substance which cannot be split up into two or more simpler substances by chemical means. Sugar is not an element as it can be broken down into carbon and water.
  • Slide 11
  • Note that an element: Consists of only one kind of atom, Cannot be broken down into a simpler type of matter by either physical or chemical means Can exist as either atoms (e.g. argon) or molecules (e.g., nitrogen). Elements
  • Slide 12
  • Examples of elements Elements are made up of tiny particles Elements can be further classified into two groups: Is the smallest particle of an element and has the same chemical properties of the element Is made up of two or more atoms that are chemically bonded together (note: these atoms are of the SAME element!!) Hi, I am from the Noble gas family and I work alone We same same!!
  • Slide 13
  • These are elements! Atoms of same element Cu copper element Na sodium element He helium element Molecules of same element H Hydrogen gas element O H OO ozone
  • Slide 14
  • Atoms An element is made of tiny particles called atoms. The atoms of an element is different from that of another element.
  • Slide 15
  • Elements- Atoms Microscopic view of the atoms of the element argon (gas phase). Consists of only one kind of atom
  • Slide 16
  • What is an atom? Examples of models of atoms: HNaCl Hydrogen atom Sodium atom Chlorine atom
  • Slide 17
  • Molecules Very few elements exists as atoms besides elements such as helium and neon. Most elements exist as molecules. For example, hydrogen is H 2. Ozone is O 3.
  • Slide 18
  • Hydrogen (H 2 ) is a diatomic molecule. Ozone (O 3 ) is a triatomic molecule. Molecules consisting of a few atoms are called polyatomic molecules.
  • Slide 19
  • Elements- Molecules Microscopic view of the molecules of the element nitrogen (gas phase). Consists of only one kind of atom
  • Slide 20
  • Examples of molecules (elements) HH NN O O O OO S SS S S S S S
  • Slide 21
  • Allotropes of Carbon molecule (element) Carbon is an element but made up of a very large molecule (also known as MACROMOLECULE) There are 3 types of carbon molecular structures C 60 Diamond Graphite
  • Slide 22
  • Chemical Symbols of Elements Chemists use symbols to represent elements. For example, O represents oxygen while Fe represents iron. ElementSymbolElementSymbol CalciumCaMercuryHg CarbonCNeonNe HydrogenHSiliconSi IronFeSodiumNa
  • Slide 23
  • Classification of Elements Metals and Non-metals There are two major groups of elements metals and non-metals. Iron is a metal. Oxygen is a non-metal. There are some elements called metalloids which behave like both metals and non-metals. Metals and non-metals are grouped separately on the Periodic Table.
  • Slide 24
  • What is an element? An element is a substance that cannot be broken down into two or more simpler substances by any chemical means. - They are arranged in the Periodic Table, classified as metals and non-metals. - They may consist of atoms of same element or molecules of the same element. Metals (excluding hydrogen) Non-metals (including hydrogen)
  • Slide 25
  • Physical Properties metals and non-metals MetalsNon-metals Shiny appearanceDull appearance Solids at r.t.p (except mercury) Gases, liquids or solids at r.t.p (room temp & pressure) Malleable, Ductile, SonorousBrittle if solid (general) High melting and boiling points Low melting and boiling points Good conductors of heatPoor conductors of heat Good conductors of electricity Poor conductors of electricity (expect carbon and graphite)
  • Slide 26
  • Summarising Elements Metals Non Metals Atoms Molecules
  • Slide 27
  • Introducing Little Miss Compounds Harlow! Hehee!!! *giggles* I am also a PURE SUBSTANCE I am made up of a fixed number of two or more elements chemically combined.
  • Slide 28
  • Compounds Note that a compound: can be broken down into a simpler type of matter (elements) by chemical means (but not by physical means), has properties that are different from its component elements, and always contains the same ratio of its component atoms.
  • Slide 29
  • A compound is a substance which is made up of two or more elements chemically combined together. What is a compound? - Chemical reactions taking place. Cu Qn: Is this a compound? It only contains one type of element. Qn: Is this a compound? HH It only contains one type of element. H O H O O Qn: Is this a compound? It is not chemically combined.
  • Slide 30
  • So, what is a compound then? O HH Water N HHH Ammonia gas Consists of two or more elements And They are chemically combined together!
  • Slide 31
  • Compounds Microscopic view of the molecules of the compound water (gas phase). Oxygen atoms are red and hydrogen atoms are white.
  • Slide 32
  • ELEMENTS COMPOUND hydrogen (colourless gas) oxygen (colourless gas) lighted splint heat, light and explosion water (colourless liquid) Making compounds from their elements Example: Making water (picture) Water molecule Oxygen molecule Hydrogen molecule mixture of hydrogen and oxygen water Example: Making water (models) heat, light and explosion
  • Slide 33
  • Making compounds from their elements Example: Making iron sulphide compound Iron + sulphur iron sulphide elements compound + yellow grey heat black
  • Slide 34
  • Little Miss Compound Property #1 I can be represented as a chemical formula The different elements present in a compound are combined in a fixed ratio General Rules: - Only write the name of the metallic element first - Write the number of atoms of any element in the compound in subscript (applies to only 2 or more atoms) - ide will always be written at the end of the non metal element Special Rules: Does not apply to organic compounds (chapter 18 onwards)
  • Slide 35
  • Little Miss Compound Property #2 I am formed by atoms of different elements. However, I do not have the properties as them. Examples Na + Cl 2 NaCl (s) (g) (s) H 2 + O 2 H 2 O (g) (g) (l)
  • Slide 36
  • Little Miss Compound Property #3 Because of my chemical bonds, I cannot be broken down by physical means. I can only be broken down by chemical reaction or electricity. Electrolysis (breaking down of compound by electricity) 2MgCl(s) Mg(s) +Cl 2 (g) Thermal Decomposition (breaking down of compound by heat) HgO(s) Hg(s) + O 2 (g)
  • Slide 37
  • How do we name compounds? Rule 1 A compound made up of two elements has a name that ends in -ide. Sodium chloride made up of the elements sodium and chlorine Zinc oxide made up of the elements zinc and oxygen Carbon dioxide made up of the elements carbon and oxygen
  • Slide 38
  • How do we name compounds? Rule 2 A compound that contains hydroxide ions, OH (a negatively charged ion made up of oxygen and hydrogen) is named a hydroxide. Potassium hydroxide contains potassium ions and hydroxide ions
  • Slide 39
  • How do we name compounds? Rule 3 A compound that contains a negatively charged polyatomic ion containing oxygen usually has a name ending in ate. Copper(II) sulphate contains oxygen atoms in the sulphate ion Sodium nitrate contains oxygen atoms in the nitrate ion