atoms

• atoms contain protons , neutrons and electrons
• the nucleus is in the middle of the cell
• nucleus contains protons and neutrons
• nucleus has a positive charge due to protons
• electrons are in shells around the nucleus
• electrons have a negative charge
• electrons mass is very small
• neutrons have a neutral charge
• neutrons have a mass of 1
• protons have a positive charge
• protons mass is 1
• atoms have no overall charge as number of protons and electrons is equal
• mass number= number of protons + number of neutrons
• atomic number tells u the amount of protons
• amount of protons= amount of electrons
• compounds are substances that are made up of two or more elements chemically combined
• an element is substance made up of only one type of atom, e.g. hydrogen
• a mixture is a substance that contains two or more different elements or compounds that are not chemically combined
• isotopes are different forms of the same element with the same number of protons but different number of neutrons