Elements, Compounds and Mixtures Ms. O’Rourke Chapter 20

Aims and objectives of the lesson OC3 understand what an element is and recall OC3 understand what an element is and recall that all known elements are listed in the that all known elements are listed in the Periodic Table Periodic Table understand what a compound is and what a mixture is understand what a compound is and what a mixture is

Elements, Compounds and Mixtures Matter exists in three states Matter exists in three states Solids Solids Liquids Liquids Gases Gases Chemists discovered that all matter, or substances, on Earth are made up of atoms. Chemists discovered that all matter, or substances, on Earth are made up of atoms.

Some substances are made up of atoms that are all the same as each other. Some substances are made up of atoms that are all the same as each other. This was discovered by an Irish Scientist This was discovered by an Irish Scientist Robert Boyle Robert Boyle

Robert Boyle (25 January 1627 – 31 December 1691) Boyle was born in Lismore Castle, in County Waterford, Ireland, the seventh son and fourteenth child of Richard Boyle, 1st Earl of Cork and Catherine Fenton.

Some substances are made up of atoms that are all the same as each other. Some substances are made up of atoms that are all the same as each other. These substances are called elements. These substances are called elements. Can you name an element? Can you name an element?

Many everyday substances are elements Homework Homework Name something we see or use everyday that is an element Name something we see or use everyday that is an element

Element song

An element A substance made up of only one type of atom. A substance made up of only one type of atom.

Elements An element is a substance made up of only one type of atom. An element is a substance made up of only one type of atom. There are over 100 different elements. There are over 100 different elements. Everything on earth is made from these elements. Everything on earth is made from these elements. They can be thought of as being like pieces of lego. They can be thought of as being like pieces of lego.

Demonstration A bar of Galaxy A bar of Galaxy chocolate is like our chocolate is like our __________________? __________________?

If I break a piece of the chocolate off what do I have? If I break a piece of the chocolate off what do I have? What is the small piece like? What is the small piece like? If I grate the bar what do the grated pieces represent? If I grate the bar what do the grated pieces represent?

Elements The atoms in solids are tightly packed The atoms in solids are tightly packed The atoms in gases often go around in pairs The atoms in gases often go around in pairs

Names and symbols of elements All the known elements are listed in a table called the periodic table. All the known elements are listed in a table called the periodic table.

Names and symbols of elements Elements are written in a particular way. Elements are written in a particular way. All elements are given are given symbols to identify them. All elements are given are given symbols to identify them. All the symbols have either one or two letters in them. All the symbols have either one or two letters in them.

The first letter is a capital letter. The second letter is always a small letter. The first letter is a capital letter. The second letter is always a small letter. Scientists all around the world use these symbols for the elements. Scientists all around the world use these symbols for the elements.

Elements and symbols HydrogenH CarbonC NitrogenN OxygenO SulfurS AluminiumAl Iron (ferrum)Fe ZincZn Silver (argentium)Ag Gold (aurum)Au Sodium (natrium)Na CopperCu

Elements and symbols Many of the symbols are obvious e.g. Carbon is C but some are not. Many of the symbols are obvious e.g. Carbon is C but some are not. This is because the symbol comes from the Latin name of that element. This is because the symbol comes from the Latin name of that element. Example the symbol for iron is Fe from the Latin word for iron, Ferrum. Example the symbol for iron is Fe from the Latin word for iron, Ferrum.

Elements and symbols Sodium is Natrium Na symbol for sodium Sodium is Natrium Na symbol for sodium Other elements are named after scientists who discovered them. Other elements are named after scientists who discovered them. Example: Curium- is named after Marie Curie and her husband Pierre Example: Curium- is named after Marie Curie and her husband Pierre Polonium is named after their home country - Poland. Polonium is named after their home country - Poland.

Research task In groups pick an element and in your groups write a few sentences on it and present it to the class. In groups pick an element and in your groups write a few sentences on it and present it to the class. List: Helium, Nitrogen, Oxygen, Aluminium, Calcium, Iron, Gold, Silver, Copper, Zinc, Carbon, Hydrogen List: Helium, Nitrogen, Oxygen, Aluminium, Calcium, Iron, Gold, Silver, Copper, Zinc, Carbon, Hydrogen

Molecules Atoms are like building blocks or Lego. When atoms join together they form molecules Atoms are like building blocks or Lego. When atoms join together they form molecules A Molecule : Composed of two or more atoms chemically combined. A Molecule : Composed of two or more atoms chemically combined.

Molecules Molecules are groups of two or more atoms joined together. Molecules are groups of two or more atoms joined together. They are the smallest part of an element or compound that can exist on its own. They are the smallest part of an element or compound that can exist on its own.

Can you name any examples of molecules?

Examples of molecules Water molecule Water molecule Methane molecule Methane molecule Carbon dioxide Carbon dioxide

Examples of molecules Hydrogen molecule Hydrogen molecule Oxygen molecule Oxygen molecule

Activity In groups draw an example of a molecule In groups draw an example of a molecule

Compounds The periodic table is made up of elements The periodic table is made up of elements (substances made up of only one type of atom) Very often two or more of these elements join together and form a new substance. Very often two or more of these elements join together and form a new substance. These new substances are called compounds These new substances are called compounds

Compounds Consist of two or more elements chemically combined. Consist of two or more elements chemically combined. Compounds are all around us Compounds are all around us Can you name any? Can you name any?

Compounds Water Water Made up of two elements hydrogen and oxygen in the ration 2:1 H 2 O Made up of two elements hydrogen and oxygen in the ration 2:1 H 2 O Table salt has the chemical formula Table salt has the chemical formula NaCl. It is made up of two elements, Na and Cl chemically combined. NaCl. It is made up of two elements, Na and Cl chemically combined. Can you name the elements Na and Cl? Can you name the elements Na and Cl?

Mixtures So far we have looked at elements and compounds. So far we have looked at elements and compounds. Elements Elements Are only made up of one type of atom Are only made up of one type of atom Compounds Compounds Have two or more elements chemically combined. Have two or more elements chemically combined.

Mixtures Are made up of two or substances mingled together but not chemically combined. Are made up of two or substances mingled together but not chemically combined. A mixture can be made up of elements or compounds but in no definite amounts A mixture can be made up of elements or compounds but in no definite amounts

Examples Air ( a mixture of gases in no definite amount) Air ( a mixture of gases in no definite amount) A pack of skittles in a mixture of different coloured sweets 3hich varies from bag to bag. A pack of skittles in a mixture of different coloured sweets 3hich varies from bag to bag.

Mixture activity sweets Separate the sweets into their colours. See the different mixture of colour. Separate the sweets into their colours. See the different mixture of colour. The different amounts of each colour in the packet. The different amounts of each colour in the packet.

Differences between compounds and mixtures CompoundsMixtures Made up of a single substance Made up of two or more substances Elements in a compound are always in a fixed ratio Amount of substances in a mixture can vary Difficult to separate the elements of a compound Usually easy to separate the substances in a mixture Properties of a compound are different to those of the elements it contains Properties of a mixture are similar to those of the substances in the mixture. There is usually a heat change when a compound is formed. Very little heat change when a mixture is made

Properties of compounds Compounds are made of different elements chemically combined. Compounds are made of different elements chemically combined. The properties of compounds are very often completely different from those of the elements from which they are made. The properties of compounds are very often completely different from those of the elements from which they are made. Here are some examples Here are some examples

Compounds elements Sodium chloride (table salt) Sodium: very reactive metal, stored under oil Chlorine: poisonous green gas Carbon dioxide (used in fire extinguishers) Carbon: black solid Oxygen: needed for substances to burn Water (liquid used in fire extinguishers) Hydrogen: explosive gas Oxygen: needed to burn substances

Recap questions and activities On show me boards answer the following On show me boards answer the following What is an element and name an element What is an element and name an element In what table do we find the elements? In what table do we find the elements?

Name an example of a moecule Name an example of a moecule What is a compound What is a compound Name a compound Name a compound What is a mixture? What is a mixture?

Activity Q9 pg 176 Q9 pg 176 Q11,12,13,14,15 Q11,12,13,14,15

Homework Q1,2,3,4,5,6 pg 175 Q1,2,3,4,5,6 pg 175