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Periodic Table
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Periodic Table Brain Pop
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He organized them by their increasing atomic masses.
Dmitri Mendeleev organized the known elements into a table called the periodic table. He organized them by their increasing atomic masses.
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Today we organize the elements by their increasing Atomic Number.
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Each square contains an element’s chemical name, atomic number, chemical symbol, and average atomic mass.
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The atomic number is listed at the top of each square
The atomic number is listed at the top of each square. As you move from left to right within a period, the atomic number of each element increases by 1.
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The chemical symbol is an abbreviation for the element’s name
The chemical symbol is an abbreviation for the element’s name. The name of the element is listed under the symbol.
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All atoms of an element have the same number of protons, but the number of neutrons can vary. The average atomic mass is the weighted average of the masses.
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A zigzag line on the periodic table divides the three major categories of elements: metals, nonmetals, and metalloids.
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Metals are elements that are shiny and conduct heat and electricity well, malleable (can bend easily into shapes), and ductile (can be drawn out into thin wires. Elements to the left of the zigzag line are metals, except for hydrogen.
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To the right of the zigzag line are the nonmetals.
Nonmetals are poor conductors of heat and electricity, and are often dull and brittle. Metalloids are elements that have some properties of metals and nonmetals.
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Rows on the periodic table are called periods
Rows on the periodic table are called periods. All the elements listed in a row belong to the same period. There are 7 (seven) periods.
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Columns in the periodic table are called groups or families
Columns in the periodic table are called groups or families. All elements in a group have similar properties.
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Insert copy of the periodic table.
The columns are numbered 1 – 18 starting at the left and moving to the right. Please make sure that your periodic table has them numbered like this.
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The outer most energy level is usually not full or complete .
Valence Electrons The outer most energy level is usually not full or complete . These electrons in the outer energy level are called Valence electrons. Valence electrons are important because they determine how an element will react with other substance.
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Insert picture of periodic table.
Groups 1 and 2: The number of Valence electrons in the outer energy level will match the group number.
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Insert picture of periodic table.
Groups 3 through 12 do not follow any particular rule to determine the number of Valence electrons.
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Insert picture of periodic table.
Group 13 to 18 – The Valence electrons for each of these is the group number less 10. For example Group 14 – 10 = 4 Valence electrons.
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Elements whose atoms gain, lose or share electrons are reactive and they combine to form the many compounds we use in our daily lives.
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Low Density (some will even float)
Group 1: Alkali Metals Soft – can be cut with a knife Shiny and silver colored Low Density (some will even float) Most reactive of the metals Valence electrons = 1 Reacts violently with water forming a hydrogen gas Compounds from these are very useful such as NaCl 3 Li Lithium 6.941 11 Na Sodium 22.990 19 K Potassium 39.098 37 Rb Rubidium 85.468 55 Cs Cesium 87 Fr Francium
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Silver colored Group 2: Alkaline- Earth Metals
4 Be Beryllium 9.012 12 Mg Magnesium 24.305 20 Ca Calcium 40.078 38 Sr Strontium 87.62 56 Ba barium 88 Ra Radium 226 Group 2: Alkaline- Earth Metals Very reactive but not as reactive as Alkali Metals. Silver colored More dense than Group 1 metals Valence electrons = 2 Useful compounds include: Calcium compounds such as cement, plaster, chalk, and YOU.
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Higher density and melting points (except mercury) than Group 1 and 2
Group 3 to 12: Transition Metals Do not lose their valence electrons as easily as groups 1 & 2. Less reactive than Alkali and Alkaline Earth metals Shiny Good conductors of electricity Higher density and melting points (except mercury) than Group 1 and 2
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Group 3 to 12: Transition Metals (cont’.)
Lanthanides: The first row underneath the periodic table: Shiny, reactive, many are used in the production of steel. Actinides: The second row underneath the periodic table: These elements are all radioactive and unstable.. Note: Elements found after 94 (Plutonium) are man made and not found in nature
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Valence electrons = 8 except helium (2) Outermost energy shell is full
4.003 10 Ne Neon 21.180 18 Ar Argon 39.948 36 Kr Krypton 83.80 54 Xe Xenon 86 Rn Radon 222 Group 18: Noble Gas Group Non-reactant Valence electrons = 8 except helium (2) Outermost energy shell is full Colorless, odorless gases at room temp. Under normal conditions they do not react with other elements All found on Earth in very small amounts Argon is the most common in the group Their non-reactivity makes them very useful for light bulbs, helium for blimps and weather balloons.
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Summary How are elements arranged on the periodic table?
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