PPT in Science 7 Week 2.pptx
- 2. Activity Read it Fast 1. Comp- found 2. Elem- mint 3. Math- tear 4. Mole- lick qules
- 5. • Matter - anything that has mass and take any space
- 7. • Element issingle matter that cannot be broken down into simpler matter by chemical methods. • There are 1 1 6known elements. Of these 92 are found in the Earth (natural). The other 24 elements have been made by scientist in laboratories (manmade). Examples of element: Fluorine Aluminium Gold silver Mercury
- 8. The Symbol of element • Rules of writing element symbols: 1. If an element issymbolized by one letter, it must be capital letter, for example oxygen (O), hydrogen (H), carbon (C). 2. If an element issymbolized by more than one letters, the first letter must be capital letter followed by small letter, for example zinc (Zn), gold (Au), copper (Cu).
- 9. Noble gases lead mercury copper boron silikon carbon chlorine neon sulphur . METAL NON- METAL METALLOID ⦿Classification of elements as metal and non- metals are classified as metals and non-metals, depending on how well they conduc electricity and heat. – Metals are good conductors and Non-metal very poor electrical conductors. – Some elements are classified as Metalloids (or semi-metals). Metalloids have properties between those of metals and non metals
- 10. Properties Metals Non-metals Ability to conduct heat and electricity Good conductor Poor conductor (except carbon) Densities, melting and boiling point Usually solids (except mercury), high densities, high melting points and boiling points Usually liquid and gases with low densities, low melting points and boiling points Appearance Usually hard and shiny Usually soft and dull Are they malleable? (mudah ditempa ) Yes No
- 11. ⦿Classification of elements as in the periodic table
- 12. What are elements made of? • Atoms An atom isthe smallest unit of an element, having properties of that element. The atoms of one element are different from the atoms of any other element. For example, all hydrogen atoms are the same and are different from atoms of carbon or iron. • Molecules Most gaseouselements form molecules comprising two atoms. Example: –Oxygen (O2), –Hydrogen (H2), –Nitrogen (N2), –Chlorine (Cl2) N N + N2 Gases N N
- 13. Post test Answer this question. • Define an element. • State the names and symbols of some common elements. • Describe ways of classifying the elements. www.chem4kids.com
- 14. • Compound isa substance containing two or more elements chemically joined together. • Compound isa single matter that cannot be broken down by physical separation. • The compound can only be broken down into its elements by a chemical reaction.
- 15. ⦿If elements combine together, they will completely change. For example: ◾Water (H2O) is a compound made up of Hydrogen and Oxygen. Hydrogen and Oxygen are colourless gases, and the compound water is colourless liquid H H O H H O +
- 16. What are Compound made of? ⦿Molecules is the smallest particle of a compound. ⦿A compound contain only one kind of molecule. ⦿Molecule is a group of two or more atoms chemically joined together.
- 17. The chemical formula for water is This formula tells us that a water molecule contains 2 hydrogen atoms and 1 oxygen atom The chemical formula of a molecule shows the number and kinds of atoms contained in it. Symbol of atom The amount of atoms present in one molecule
- 18. • In the world, there are many things that’s not pure substances. • Mixtures consist of two or more substances that are not chemically joined together. • Mixtures can consist of elements, compounds a water is mixture of compounds including water and sodium chloride Brass is a mixture of the elements copper
- 19. Homogeneous The prefixes: "hetero"- indicate difference. A heterogeneous mixture consists of visibly different substances or phases. The three phases or states of matter are gas, liquid, and solid. Heterogeneous The prefixes "homo"- indicate sameness A homogeneous mixture has the same uniform appearance and composition throughout. Many homogeneous mixtures are commonly referred to as solutions. In sugar solution, sugar is the solute and water is the solvent