SCIENCE Q2

• The periodic table is the most useful tool to a chemist as it organizes information about all the known elements.
• Johann Dobereiner was the first chemist to recognize that groups of elements with similar properties exist, known as a triad.
• John Newlands devised the first periodic table, arranging elements in order of increasing atomic mass and law of octaves.
• Dmitri Ivanovich Mendeleev is known as the “father” of the Periodic Table as he arranged the elements in the periodic table in order of increasing atomic mass.
• Henry Moseley, in 1913, determined the actual nuclear charge (atomic number) of the elements through his work with X-rays.
• Henry Moseley rearranged the elements in order of increasing atomic number.
• The Periodic Law states that when elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties.
• The atomic mass is how much the element weighs.
• All elements’ masses are different.
• The atomic number is how many Protons are in the nucleus.
• Metals are good conductors of heat and electricity.
• Metals are shiny.
• Metals are ductile and can be stretched into thin wires.
• Metals are malleable and can be pounded into thin sheets.
• A chemical property of metal is its reaction with water which results in corrosion.
• Solid at room temperature except Hg.
• Non-metals are poor conductors of heat and electricity.
• Non-metals are not ductile or malleable.
• Solid non-metals are brittle and break easily.
• Non-metals are dull.
• Many non-metals are gasses.
• Metalloids have properties of both metals and non-metals.
• Metalloids are solids that can be shiny or dull.
• Metalloids conduct heat and electricity better than non-metals but not as well as metals.
• Metalloids are ductile and malleable.
• HYDROGEN is a reactive diatomic gas
• HYDROGEN is a promising alternative for fuel
• ALKALI EARTH METALS are GROUP 1
• ALKALI EARTH METALS are very reactive and mixed with something in nature
• ALKALI EARTH METALS are soft to cut with a butter knife
• ALKALINE EARTH METALS are found in GROUP 2
• TRANSITION METALS are found in GROUPS 3-12
• BORON GROUP is found in GROUP 13
• CARBON FAMILY is found in GROUP 14
• NITROGEN GROUP is found in group 15
• OXYGEN or CHALCOGENS are found in GROUP 16
• HALOGENS are found in GROUP 17
• NOBLE GASSES are found in GROUP 18
• ELECTRON is important for the formation of chemical bonds
• NEILS BOHR invented the planetary model