Elements and compounds

• Vertical columns of elements with similar properties are called groups.
• The horizontal rows are called periods.
• Alloys are mixtures of metals designed to have properties that are useful for a particular purpose.
• Metals are usually solids and their mpt is bpt is high.
• Non-metals are solids or gases, except for bromine which is a liquid at room temp and their mpt and bpt are often low.
• Metals are usually hard and dense.
• Most non-metals are softer than metals, but diamonds are very hard.
• Metals can change shape when they are hammered because they are malleable.
• Most non-metals are brittle as a solid.
• The vertical groups in a periodic table show how elements within the same group have similar chemical and physical properties.
• The first row of transition metals is group 4.
• The noble gases are the least reactive elements in the periodic table.
• Group 1 (or alkali metals), are the most reactive elements.
• Group 1 metals are stored in oil to prevent them from reacting with oxygen and water vapor in the air.
• Reactivity in group one increases as you go down the group.
• All group 1 metals react with water to form hydrogen and an alkaline solution of the metal hydroxide.
• Melting point becomes lower while density of the metals increase as you go down the elements of group 1.
• The most reactive non-metals are halogens.
• The reactivity decreases down the halogen group.
• Fluorine is very reactive
• Fluorine is a pale yellow gas at room temperature.
• Elements change from gases to solids as you go down group 7.
• Chlorine is a dense pale green gas.
• Chlorine is smelly and poisonous.
• Bromine is a deep red liquid with red-brown vapor.
• Bromine is smelly and poisonous.
• Iodine is a gray solid with purple vapor.
• Iodine is smelly and poisonous.
• Test for chlorine gas: Damp litmus or universal indicator is bleached when held in gas.
• Helium is used in airships and balloons because it is light and unreactive.
• Mpts and bpts of noble gases are extremely low.
• Noble gases are stable.
• Change in properties centers around silicon.
• Group 7 elements gain or share electrons and Group 1 elements lose or share electrons.
• Transition metals have good corrosion resistance.
• Steel nails, bottle stoppers, pipe joints are all made from transition metals.
• Transition metals are often colored.
• Transition metals are strong, hard, and have high density, mpt, and bpt.
• Metals are held together with metallic bonding.
• Non-metallic elements are held together by covalent bonds.