the periodic law dmitri mendeleev (1860) when the elements are placed in order by increasing atomic...
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The Periodic LawThe Periodic Law
Dmitri Mendeleev (1860) When the elements are placed in order by increasing atomic mass, their properties repeat in a periodic way.
Moseley (~1910)
Changed the elements’ order from atomic mass to atomic number.
An atom’s chemical properties are determined by its valence (outside energy level) electrons. The identity of the element (what element an atom is) is determined by the number of protons it has.
Protons
Atoms tend to lose, gain or share electrons in order to get an electron configuration like a noble gas.
Elements are arranged:
Vertically into Groups
Horizontally Into Periods
Arrangement of Table
Metals
Metalloids
Nonmetals
Metals
• Over 75% of the elements are classified as metals.
• They are located to the left and lower parts of the periodic table.
a. Malleable a. Capable of being shaped or formed by being
hammered
b. Usually shiny, gray coloredc. Conduct electricity d. Conduct heate. Ductile
a. Capable of being drawn out into a wire
f. Usually solids at room temperature
Properties of Metals
Metals Form Cations & Metals Form Cations & AlloysAlloys
Metals Form Cations & Metals Form Cations & AlloysAlloys
A CATION forms when an atom loses one or more electrons.
Metals are mixed with other metals to form alloys.
Mg --> Mg2+ + 2 e- Stainless Steel Refrigerator
Nonmetals
• They are found in the upper right part of the table.
Metals
Metalloids
Nonmetals
Nonmetal properties are more diverse than the metals.
• solid, liquid, or gas at room temp
•usually poor heat conductors
•usually poor electrical conductors
•solids are brittle
An ANION forms when an atom gains one or more electrons
Nonmetals Form AnionsNonmetals Form AnionsNonmetals Form AnionsNonmetals Form Anions
Metalloids (also called semimetals)
• They are found on the table between the metals and the nonmetals.
Metals
Metalloids
Nonmetals
•They have properties of both metals and nonmetals.
Examples are silicon, arsenic, and germanium
Periods (Energy Levels)
• There are 7 periods in the periodic table.
• The inner transition metals are actually “inside” periods 6 and 7.
Horizontally Rows
Periodic Trends
• Across a period, atomic radius tends to decrease .
• Across a period, ionization energy tends to increase .
Elements are arranged:
Vertically into
Groups (also called chemical families)
Groups
• Eight tall groups of main group (representative) elements, numbers ending in A, or #1-2 & 13-18.
• Ten shorter groups of transition metals, numbers ending in B or #3-12.
• Elements in the same group have the same valence electron configuration, and therefore have similar chemical and physical properties.
Down a group, atomic radius increases and
ionization energy decreases.
Increasing
Increasing
Alkali Metals
reacting with water:
• Li (Lithium) – least reactive
• Na (Sodium)
• K (Potassium)
• Rb (Rubidium)• Cs (Cesium) – more reactive
What would you expect from Francium?!?!
Group or Family Members
Group 1A: Alkali Metals Group 1A: Alkali Metals PropertiesProperties
Group 1A: Alkali Metals Group 1A: Alkali Metals PropertiesProperties
Group 1A: Alkali Metals Group 1A: Alkali Metals PropertiesProperties
Group 1A: Alkali Metals Group 1A: Alkali Metals PropertiesProperties
2) Highly reactive with H2O to form alkaline solution.
Valence electron configuration (period)s1
1) Soft, silver-colored metals
Group 1A: Alkali Metals Group 1A: Alkali Metals Properties cont.Properties cont.
Group 1A: Alkali Metals Group 1A: Alkali Metals Properties cont.Properties cont.
3) They tend to form +1 ions
4) Low density (some float in water
Li --> Li1+ + 1 e-
They are part of the s block.
Now get one color and outline the Alkali Metal Family.
Group 2A: Alkaline Earth Metals
Silvery-White Metals
Many are found in rocks in the earth’s crust
Group 2A: Alkaline Earth Metals cont.
Valence electron configuration (period) s2
Group 2A: Alkaline Earth Metals Properties
1)react w/water to form alkaline solution
2)not as reactive as Group 1
3)not as soft as Group 1
4)tend to form +2 ions Mg --> Mg2+ + 2 e-
Part of the s-block
Now get one color and outline the Alkaline Earth Metal Family.
Groups 3B through 2B or 3 through 12 Transition Metals
Groups 3B through 2B or 3 through 12 Transition Metals
Properties
1) often form colored compounds
2) harder than Groups 1 and 2
Groups 3B through 2B or 3 through 12 Transition Metals
Many of these elements can form ions with varying charges, such as Fe+3/Fe+2, Cu+2/Cu+1
Part of the d-block
Now get one color and outline the Transition Metals
Groups 3A or 13: Boron Family (sometimes known as Aluminum
Family)
Valence electron configuration (period) s2 p1
Properties become more metallic down the group.
Part of the p -block
Now get one color and outline the Boron Family (sometimes known as Aluminum Family)
Groups 4A or 14: Carbon Family
nonmetals C
metalloids Si, Ge
metals Sn, Pb
Groups 4A or 14: Carbon Family cont.
Valence electron configuration (period) s2 p2
Properties become more metallic down the group.
Part of the p -block
Groups 4A or 14: Carbon Family cont.
Elements that exist in more than one form are called allotropes.
An example is carbon in forms of
Graphite Diamonds Buckyballs Amorphic
Now get one color and outline the Carbon Family
Group 5A or 15: Nitrogen Family
nonmetals N, P
metalloids As, Sb
metals Bi
Group 5A or 15: Nitrogen Family
Valence electron configuration (period) s2 p3
Properties become more metallic down the group.
Nonmetals tend to form ions with - 3 charge.
Part of the p -block
N --> N3- + 3 e-
Now get one color and outline the Nitrogen Family
Group 6A or 16: Oxygen Family
nonmetals O, S, Se
metalloid Te
metals Po
Valence electron configuration (period) s2 p4
Group 6A or 16: Oxygen Family
Properties become more metallic down the group.
Nonmetals tend to form ions with - 2 charge. O --> O2- + 2 e-
Part of the p -block
Important allotropes from this group are oxygen in forms O2, oxygen gas and O3, ozone
Now get one color and outline the Oxygen Family
Group 7A or 17: Halogen Family (“saltmakers”)
Members – all nonmetals F, Cl, Br, I, At
Valence electron configuration (period) s2 p5
Part of the p -block
Group 7A or 17: Halogen Family (“saltmakers”) cont.
Very reactive, electronegative (measurement of the attraction for electrons) because these atoms need only one electron to have the same electron configuration as a noble gas.
Tend to form ions with - 1 charge.
F --> F1- + 1 e-
Now get one color and outline the Halogen Family
Group 8A or 18: Noble Gases
Sometimes called “inert gases,” though most can be made to react.
Valence electron configuration for He 1s2, all others (period) s2 p6
Group 8A or 18: Noble Gases cont.
Properties
1. all are gases at room temp
2. relatively unreactive
Part of the p -block
They have no common ionic charge because they don’t form ions, have stable electron configurations
Now get one color and outline the Noble Gases
Inner Transition Metals
Usually considered together because of their similar properties.
Belong inside periods 6 and 7, but are moved to fit on a page better.
Elements 57-71 are called the lanthanides; 89—103 are the actinides.
Inner Transition Metals cont.
Part of the f block
Many of these are radioactive (have unstable nuclei); Pm and all elements past uranium are radioactive.
Tend to form ions with +3 charge.
Now get one color and outline the Inner Transition Metals
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