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Elements Notes Name: ______________________( ) Class: 1 ____ Date: ____________ Elements An element is a substance which cannot be broken down into two or more simpler substances by chemical methods. Elements are the simplest kind of matter. There are more than 100 elements in the universe. All discovered elements are listed in the Periodic Table. The Periodic Table Every element is represented by a unique symbol of one or two letters. If there are two letters in the symbol, the 2nd letter must be a small letter! E.g. CO (____________________________) is not the same as Co (_______________)! 1 Every element in the Periodic table is given a unique number called the atomic number. The atomic number is at the bottom left corner of the element’s box. Activity - Name the elements! Symbol Element Atomic Number Symbol H Mg O He N Ne C Cl Au Hg Ag Na Cu Fe Al S Zn I Element Atomic number Classifying elements The periodic table is a very organised system. Elements have been placed systematically into the Periodic Table according to their properties. Scientists have classified elements into 2 main groups, the metals and non-metals. Each vertical column is called a _____________________. Each group’s number is reflected at the top of the periodic table. Elements in the same group have similar ________________________ and will undergo the same type of chemical reactions. Each group has its own unique properties. Each horizontal row is called a _____________________. The periods are numbered from the top row down. Elements in a period from left to right show a gradual change from ________________________ to ________________________. 2 Elements to the left of the zig-zag line in the Periodic Table are metals, while those to the right of the zig-zag line are non-metals. Metals vs Non-metals General Properties Metals Non-metals Examples Appearance Electrical and heat conductivity Melting/boiling point Ductility (ability to be drawn into wires) and malleability (ability to be flattened into sheets) Density Ability to produce sound when hit Activity - Without looking at the periodic table, circle the metals in the list! Silver, Gold, Helium, Neon, Titanium, Hydrogen gas, Platinum, Nitrogen gas, Chlorine gas 3 Uses of some common metals (Note: The chemical formula of a metal is always just its element symbol.) Element / Chemical formula Uses Aluminium (Al) Zinc (Zn) Copper (Cu) Magnesium (Mg) Mercury (liquid) (Hg) Iron (Fe) More ACE ideas to think about: If metals can be easily flattened into sheets and drawn into wires, why are our metal pots and pans so hard? What is steel? It cannot be found in the periodic table – so it is not an element! On the same note, what is brass? Or bronze? What is 12K/18K/24K gold? What is the difference between the different types of gold? All these questions can be answered with one key word – do you know what it is? 4 Uses of some common non-metals (Note: The chemical formula of a non-metal will usually have a subscript to the right of the symbol. This number represents the number of atoms in a molecule of the element. For example, Cl2 means that there are 2 Cl atoms in a molecule of chlorine gas. You will learn more about this in Sec 2 and Upper Sec Chemistry However, if you are interested to read up more, go ahead!) Element / Chemical formula Uses Note: Carbon exists in various forms known as allotropes (what are allotropes? - possible ACE idea!) Graphite: Carbon (solid) (C) Diamond: Charcoal: Sulfur (solid) (S8) Chlorine gas (Cl2) Nitrogen gas (N2) Iodine (solid) (I2) Hydrogen gas (H2) Oxygen gas (O2) 5