Periodic Table. The Periodic Law Elements are arranged by increasing atomic number What is atomic...
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Transcript of Periodic Table. The Periodic Law Elements are arranged by increasing atomic number What is atomic...
The Periodic Law
• Elements are arranged by increasing atomic number• What is atomic number?
• Period – A row in the table of elements• Varies in number of available orbitals (this will make
sense later)
• Group – A column in the periodic table• Elements within a group have similar properties
• Periodic Law – Patterns of repeating properties
Atomic Mass
• All Periodic Tables usually contain: 4 pieces of information:
• Name of the Element• Symbol of the Element• Atomic Number• Atomic Mass – Average distribution of naturally
occurring masses and their isotopes
Classes of Elements
• Metals • Good conductors of electricity and heat• Most are malleable, ductile, solid at room temperature (except for mercury)
• Transition Metals• Able to form compounds with distinctive colors• Iron or chromium can make glass green• Copper or gold can make glass red• Cobalt makes glass blue
• Nonmetals• Poor conductors of heat and electricity• Low boiling points, some are gases at room temperature, brittle (if solid at
room temp)
• Metalloids• Have properties that fall between those of metals and nonmetals
• Properties become LESS METALLIC AND MORE METALLIC across a period
Valence Electrons
• Valence Electrons – an electron that is in the highest occupied energy level of an atom• Play a key role in chemical reactions• Valence electrons INCREASE across a period• Elements in a group have similar properties because
they have the same number of valence electrons
Alkali Metals
• Look at your Periodic Table• Group 1• Called ALKALI METALS• Have 1 valance electron• Extremely reactive• Found in nature only in compounds• Example• Table Salt – Sodium Chloride - NaCl
Alkaline Earth Metals
• Group 2• Called ALKALINE EARTH METALS• Have 2 valance electrons• Very reactive• Reacts with water• Example• Calcium have essential biological functions (Calcium
Carbonate CaCO3)
The Boron Family
• Group 3• Called the Boron Family• Have 3 valance electrons• Contains metals and metalloids• Example• A compound of boron, silicon, and oxygen is used to make
a type of glass that does not shatter easily when it undergoes a rapid change in temperature
The Carbon Family
• Group 4• Called the Carbon Family• Have 4 valance electrons• Contains nonmetals, metals, and metalloids• Example• Silicon carbide – used to tip saw blades, making them last
longer than steel blades
The Nitrogen Family
• Group 5• Called the Nitrogen Family• Have 5 valance electrons• Contains nonmetals, metals, and metalloids• Example• Red phosphorus is used on match tips to ignite them.
The Oxygen Family
• Group 6• Called the Oxygen Family• Have 6 valance electrons• Contains nonmetals and metalloids• Example• Sulfuric acid is used to make fertilizers
The Halogens
• Group 7• Called the Halogens• Have 7 valance electrons• Contains nonmetals• Example• Fluorine is used to prevent tooth decay
The Noble Gases
• Group 8• Called the Noble Gases• Have 8 valance electrons• Contains nonmetals• Example• Used in neon signs• Helium – pink• Neon – orange/red• Argon – purple• Krypton – white• Xenon - Blue
Octet Rule
• Octet Rule – The tendency for all elements to want to have EIGHT electrons by gaining or losing electrons and forming ions
• Ion – An atom or group of atoms that has a positive or negative charge