TOPIC 3 PERIODICITY 3.1 PERIODIC TABLE

ESSENTIAL IDEA The arrangement of elements in the periodic table helps to predict their electron configuration. NATURE OF SCIENCE (1.9) Obtain evidence for scientific theories by making and testing predictions based on them – scientists organize subjects based on structure and function; the periodic table is a key example of this. Early models of the periodic table from Mendeleev, and later Moseley, allowed for the prediction of properties of elements that had not yet been discovered.

INTERNATIONAL-MINDEDNESS The development of the periodic table took many years and involved scientists from different countries building upon the foundations of each other’s work and ideas.

THEORY OF KNOWLEDGE What role did inductive and deductive reasoning play in the development of the periodic table? What role does inductive and deductive reasoning have in science in general?

THE PERIODIC TABLE The elements on the Periodic Table are arranged in order of increasing atomic number which is the number of protons in the nucleus. There are over 110 elements recognized by the IUPAC and the search for elements that exist in nature is over. The only way to extend the Periodic Table is to make elements artificially.

The Periodic Table was first proposed in 1869 by the Russian chemist Dmitri Mendeleyev. He grouped the known elements into families, leaving gaps corresponding to elements that should exist but had not yet been discovered. Chemistry is not the study of a random collection of elements, but of the trends and patterns in their chemical and physical properties.

The IB data booklet Periodic Table labels the groups 1 to 18. The numbers 1A to 8A on the classroom periodic table are known as the representative or main group elements. The gap between groups 2A and 3A (columns 3-12) is filled by the transition elements. Be familiar with the location of the lanthanides and actinides at the bottom of the Periodic Table.

GUIDANCE The group numbering scheme from group 1 to group 18, as recommended by IUPAC, should be used.

UNDERSTANDING/KEY IDEA 3.1.A The periodic table is arranged into four blocks associated with the four sub-levels – s, p, d, and f.

UNDERSTANDING/KEY IDEA 3.1.B The periodic table consists of groups (vertical columns) and periods (horizontal rows).

UNDERSTANDING/KEY IDEA 3.1.C The periodic number (n) is the outer energy level that is occupied by electrons.

The rows on the Periodic Table are called periods. ◦ The period number (n) is the outermost energy level. The columns are called groups. ◦ The group number of the representative elements 1A – 8A give the number of valence electrons.

UNDERSTANDING/KEY IDEA 3.1.D The number of the principal energy level and the number of the valence electrons in an atom can be deduced from its position on the periodic table.

The row tells you the energy level. The number of electrons in the outer shell tells what Group or column to which the element belongs. You may be given an element and asked how many outer shell electrons exist. This is simply found by looking at the Group number (We have always referred to it as the “pink” number on our classroom Periodic Table.)

UNDERSTANDING/KEY IDEA 3.1.E The periodic table shows the positions of metals, non-metals and metalloids.

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Metals ◦Good conductors of heat and electricity ◦Malleable – can be beaten into thin sheets ◦Ductile – can be drawn into wires ◦Shiny or have luster ◦Tend to lose electrons in chemical reactions Non-metals ◦Poor conductors of heat and electricity ◦Tend to gain electrons in chemical reactions ◦Can be solid, liquid or gas Metalloids ◦Have both metallic and non-metallic properties

GUIDANCE The terms alkali metals, halogens, noble gases, transition metals, lanthanides and actinides should be known.

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APPLICATION/SKILLS Be able to deduce the electron configuration of an atom from the element’s position on the periodic table and vice versa.

Classroom practice.

Citations International Baccalaureate Organization. Chemistry Guide, First assessment Updated Brown, Catrin, and Mike Ford. Higher Level Chemistry. 2nd ed. N.p.: Pearson Baccalaureate, Print. Most of the information found in this power point comes directly from this textbook. The power point has been made to directly complement the Higher Level Chemistry textbook by Catrin and Brown and is used for direct instructional purposes only.