5.2 The Modern Periodic Table

5.2 The Modern Periodic Table A. How is the modern periodic table organized?

1. Mendeleev’s Periodic Table- arranged by order of increasing

atomic mass2. Modern Periodic Table – arranged

by order of increasing atomic number.

Atomic number = number of protons = number of electrons

http://concepts.ck12.org/preview/atomic-number.png

5.2 The Modern Periodic Table 3. Periods a. Row on the periodic table

b. As the atomic number increases, the number of energy levels filled increases, so more rows are filled in the periodic table.

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5.2 The Modern Periodic Table 4. Groups

a. Column in the periodic table.

b. Similar properties are found within groups. 1. Electron configurations

are similar. 2. Chemical properties

are then similar.http://rpsec.usca.edu/Courses/AEDS453L/periodictable%20copy/table_cols.gif

5.2 The Modern Periodic Table 5. Periodic Law- Pattern of repeating properties on the periodic

table when the table is arranged by increasing atomic number.

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5.2 The Modern Periodic Table B. What does the atomic mass of an element depend upon? 1. Distribution of the element’s isotopes in nature

a. Most elements are a mixture of 2 or mores isotopes. b. Each isotope exists in differing amounts (%).

2. Masses of the element’s isotopes.

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5.2 The Modern Periodic Table 3. Scientists use carbon as the standard to determine the

mass of an element

a. An atom is so incredibly small, so using the unit of grams would not be useful.

b. Atomic mass unit (amu) is 1/12 of the mass of a carbon-12 atom.

.

http://web.sahra.arizona.edu/programs/isotopes/images/carbon.gif

5.2 The Modern Periodic Table C. What categories are used to classify elements on the

periodic table? 1. Solids, Liquids and Gases

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5.2 The Modern Periodic Table 2. Elements that occur naturally and those that are man made.

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5.2 The Modern Periodic Table 3. Metals, Nonmetals or Metalloids

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5.2 The Modern Periodic Table a. Properties of Metals

1). Good conductors of heat and electricity 2). Mostly solids at room temperature 3). Malleable- can be pounded in sheets 4). Ductile – can be drawn into wires 5). Shiny 6). Most abundant type of elements

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5.2 The Modern Periodic Table b. Properties of nonmetals

1). Do not conduct heat and electricity

2). Insulators

3). Dull

4) Brittle

5). Low boiling points

6). Many are gases at room temperature

7). Some very reactive, other not reactive at all.

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5.2 The Modern Periodic Table c. Properties of metalloids (also called semiconductors) 1). Ability to conduct heat and electricity varies with temperature 2). Found between metals and non metals on periodic table 3). Only 8: B, Si, Ge, AS, Sb, Te, Po, and At

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5.2 The Modern Periodic Table D. How do properties vary across a period in the periodic table? 1. Across a period from left to right, the elements become less

metallic and more nonmetallic in their properties. 2. The most reactive metals are on the left in Group 1, the most reactive nonmetals are on the right in Group 17.

5.2 The Modern Periodic Table Review Questions:

1. What determines the atomic mass of an element? a. the natural distribution of isotopes and the atomic numbers of those

isotopesb. the natural distribution of isotopes and the masses of those isotopesc. the mass of the isotope of the element that has the most neutronsd. the average number of protons in the element’s nucleus

5.2 The Modern Periodic Table2. Which of the following is not characteristic of metals?

a. ductileb. good electrical conductorc. typically solid at room temperatured. Brittle

5.2 The Modern Periodic Table3. Within a period of the periodic table, how do the properties of the

elements vary? a. Metallic characteristics increase from left to right.b. Metallic characteristics decrease from left to right.c. Reactivity increases from left to right.d. Reactivity decreases from left to right.

5.2 The Modern Periodic Table 4. In the modern periodic table, elements are arranged in order of

increasing atomic mass.

TrueFalse