The Periodic Table

Essential Question.  How exactly are elements arranged on the periodic table?   SPS4. Students will investigate the arrangement of the Periodic Table. a. Determine the trends of the following: Number of valence electrons Types of ions formed by representative elements Location of metals, nonmetals, and metalloids Phases at room temperature b. Use the Periodic Table to predict the above properties for representative elements.

The Periodic Table

Basic Arrangement  THE ELEMENTS ON THE PERIODIC TABLE ARE ARRANGED IN ORDER OF INCREASING ATOMIC NUMBER!!!!

Groups and Periods  Period is the term used to describe a horizontal row on the periodic table.  There are 7 periods shown on your periodic table  Group and family are terms used to describe a vertical column on the periodic table.  There are 18 groups shown on your periodic table

Metals, Metalloids, and Nonmetals Metals, Metalloids, and Nonmetals  The three major categories of elements are metals, metalloids, and nonmetals.  The metals are found to the left of the Periodic table  The non - metals are found to the right of the Periodic table  Metalloids are found between the two and exhibit characteristics of both metals and nonmetals.

Synthetic Elements  The most recently discovered man-made elements are found at the bottom of the periodic table.  They are mainly radioactive

Valence Electrons  Remember……  The number of electrons that an atom of a given element contains is the same as the number of protons which is its atomic number  number of electrons= number of protons =atomic number

Valence Electrons  Remember……  Electrons exists in the electron cloud at specific energy levels Electron Level 2 Level 1

Energy Levels  Each level has a specific number of electrons that it can accept.  We can tell how many energy levels are occupied in a given element by recognizing that the period in which an element appears on the periodic table indicates the number of occupied energy levels .... EnergyLevel Number of electron

We will learn about the first four energy levels

Valence Electrons Example. Hydrogen has 1 electron It has 1 Valence electron It’s Valence number is 1 The number of electrons in an atom’s outermost energy level is called it’s Valence Number. The electrons in an atom’s outermost energy level is called it’s Valence electrons.

Groups and Valence  The group an element is in determines it’s Valence number…. Grou p Name Valenc e 1 Alkali metals 1 2 Alkaline Earth Metals Oxygen group 6 17Halogens7 18 Nobel Gasses 8 (Except He)

Atoms are unstable  An atom is unstable unless it contains a completely full outer shell.  This means 8 valence electrons (or 2 for the smaller atoms)  Atoms that do not contain 8 valence electrons tend to gain, lose or share valence electrons in order to achieve stability.

Ions  Atoms that lose electrons become positively charged.  POSITIVE IONS are called CATIONS  Atoms that gain electrons become negatively charged  NEGATIVE IONS are called ANIONS

Only Group 18 elements are stable!!!  All group 18 elements have atoms that contain 8 valence electrons (or 2 for helium).  They all have complete outer energy shells.  They are stable and do not readily gain nor lose electrons.  They are not reactive.

The atoms of the other groups are unstable!! All other groups have incomplete outer shells. This makes them NOT STABLE

The atoms of the other groups are unstable!!  Atoms have to gain, lose or share valence electrons in order to achieve stability.  The number they lose or gain, or if they share electrons, depends on the group they are in. Group 1 lose 1 2 lose 2 13 lose/ Share 3 14 Share 4 15 Gain 3/Share 5 16Gain2 17 Gain 1 18 Not Reactive

Group 1 Group 1 elements are called ALKALI METALS. They have one valence electron on their outer energy level They lose 1 electron to become stable +1 CATIONS They do so by transferring it to another atom that needs the electron. Ex. Sodium

Group 2 Group 2 elements are called ALKALI EARTH METALS. They have TWO valence electron on their outer energy level They lose 2 electrons to become stable +2 CATIONS They do so by transferring them to another atom/atoms that needs the electron Ex. Magnesium

Group 17 Group 17 elements are called Halogens They have seven valence electron on their outer energy level They gain 1 electron to become stable -1 Anions They do so by accepting it from another atom/atoms that need to lose their electrons Ex. Iodine accepts an electron from Potassium.

Group 16 Group 16 elements are called the oxygen group They have six valence electron on their outer energy level They gain 2 electron to become stable -2 ANIONS They do so by accepting them from other atom/atoms that need to loose their electrons Ex. Sulfur accepts two electrons from Magnesium.

Ionic Bonding  When atoms transfer electrons to become stable compounds, an ionic bond is formed.  The ions are kept together by their opposite charges. Ex…  Sodium (Na) reacts with Chlorine (Cl) to give Sodium chloride ( NaCl) -+

Atoms also share electrons to become Stable! Hydrogen and oxygen share electrons so they can both become stable. This is covalent bonding Some atoms of the same type share electrons so they can become stable also Ex. Nitrogen and oxygen + = = =+

Ionic Or Covalent???