5.5 5.7 Elements & Periodic Tables

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The Structure of an Atom

All matter is composed of tiny particles called atoms. Atoms are composed of subatomic particles. These subatomic particles include: • electrons (- charge), • protons (+ charge), and • neutrons ( no charge). Protons and neutrons are composed of quarks.

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The Periodic Table

What you need to know about the periodic table: • Group (column) o similar chem. properties o Roman numeral group = # of valence electrons • Period (row) o each row represents an electron orbit / shell • Elements can be grouped using several classification systems: o Metals, non-metals, and metalloids. o Representative elements, transition elements, and inner transition elements. o Chemical Families (Groups):
Alkali metals H is unique and
Alkaline earth metals, belongs in a
Halogens, and group by itself.
Noble gases.

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Drawing Bohr Diagrams

This type of diagram summarizes the numbers and positions of subatomic particles in an atom. Needed info:  Each orbital carries a maximum number of electrons. ORBIT Max # of electrons

1

2

3

4

5

6

7

2

8

8

18

18

32

32

 The PERIOD (horizontal row) represents the # of orbits surrounding the nucleus.  The GROUP NUMBER (vertical column) represents the # of valence electrons.  Number of protons, neutrons is represented by the chemical symbol, and number of electrons is the same as the atomin. Examples:

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Becoming stable… Atoms want to have a stable electron arrangement – that of the closest noble gas. This task is achieved by losing or gaining electrons in the valence shell. As soon as an atom loses or gains electrons it becomes an ion. Ions are atoms with an overall charge. Metals have a tendency to lose electrons and become positively charged. Positively charged ions are called cations. Nonmetals have a tendency to gain electrons and become negatively charged. Negatively charged ions are called anions.