review sheet.

Target Language or Knowledge:

What is a chemical? A chemical is a form of matter. 2 What are chemicals made of? Very small particles of matter called atoms. 3 Some chemicals, such as gold, mercury and oxygen gas, are classified as elements. What does the term ‘element’ mean? An element is a simple chemical made of only one type of atom. 4 Most chemicals are not elements. What are they classified as? compounds 5 A test for whether a chemical is an element or not is whether it can be broken down into simpler chemicals. What experiment can be used to confirm that water is not an element? When an electrical current is passed through water under certain conditions hydrogen gas can be collected at one electrode and oxygen gas at the other. Water can be broken down into simpler substances. 6 Why does the chemical formula for water (H2O) suggest that it is not an element? Water molecules are made of two different types of atoms - hydrogen atoms and oxygen atoms. Elements are made of only one type of atom. 7 Elements can be classified as either metals or non-metals. What do metal elements have in common? They are solid, strong, shiny (when clean), silvery, bendable and conduct heat and electricity. Chemical Symbols 1 What are two rules used in naming elements? a) Each element is given a unique name. b) Each element is given a unique one- or two-letter symbol. 2 What are the names of the elements that the following symbols stand for? • H – hydrogen • C – carbon • N – nitrogen • O – oxygen • Cl – chlorine • Mg – magnesium • S – sulfur • He – helium • Cu – copper • Si – silicon  Mixtures 1 What is a mixture? An impure substance that occurs when different chemicals are mixed together without a chemical reaction occurring. 2 Why would sandy sugar be classified as a mixture? Because the sand and the sugar grains still retain their original properties. Compounds 1 What is a compound? A chemical formed when different types of atoms are bonded together in a reaction. 2 What must occur for a compound to be formed out of several elements? a chemical reaction 3 How would you know from the formula of a chemical that it was a compound? The formula would have the symbols for several different types of atoms.

matter atoms elements element atom elements compounds broken down chemicals hydrogen oxygen Water water element different atoms oxygen Elements metals non-metals common unique symbol hydrogen carbon nitrogen oxygen chlorine magnesium sulfur helium copper silicon impure chemical original chemical reaction symbols different