Vocabulary

• light up: To illuminate something; to make something brighter with light.
• next to: Being located along side another
• on to: Toward something; forward
• period: Set amount of time during which events take place
• grow: To get bigger and more mature; make plants do this
• react: To change when mixing with other chemicals
• stable: In a position where something does not fall over
• noble: Being admirable and honorable in character
• gas: Elements in our air, like oxygen or nitrogen
• table: Diagram that shows data in rows and columns
• periodic: Happening regularly, but not frequently
• outer: Far away
• chlorine: Greenish-yellow gas with a strong smell
• arsenic: Strong poison used as insecticide, etc.
• radium: Radioactive element occurring in uranium ore
• cobalt: Hard, shiny, silver-white metal
• radon: Radioactive gas coming naturally from the ground
• thorium: Soft silvery-white tetravalent radioactive metallic element; isotope is used as a power source in nuclear reactors; occurs in thorite and in monazite sands