Compounds Atoms have a tendency to combine and form new materials. A bond is a kind of glue that holds atoms together to form new particles of a compound. What compound is this? 

Metals Generally, elements that have three or less electrons in the outer energy level are called metals. Metals are found on the left hand side of the periodic table.

Examples of Metals Chromium: Used in making stainless steel. Barium: Used in glassmaking and in rat poison Scandium: Used in high intensity lights. Thallium: Used in ant killer and in treating ringworm (in small, controlled amounts)

Non-Metals Elements that have five or more electrons in the outer energy level are classified as non-metals. Non-metals are found on the right hand side of the periodic table.

Examples of Nonmetals Sulfur: Used in making matches and in pyrotechnics Neon: Used in light signs and in lasers. Fluorine: Used in rocket fuel. Radon: Naturally occurring gas that can be a side product of nuclear power plants.

Metalloids There are exceptions to this general classification and some families have members that behave as both metals and non-metals (e.g., silicon). These elements are called metalloids. Many periodic tables have stair steps across families at the right side. The elements on the dividing line are metalloids.

Examples of Metalloids Boron: Used in fighter aircrafts and in soaps. Arsenic: Used in the treatment of cancer, but can be poisonous in large amounts. Silicon: Used in electronics and automotive parts.

Ionic Bonds Ionic bonds result when electrons are transferred from metal atoms to non-metal atoms. The metal atoms lose electrons to become positive ions, while the non-metal atoms gain electrons to become negative ions. The ions are then held together by the action of opposite charges in an ionic bond.

Metal element + non-metal element = ionic bond 1)Which element is the metal? 2)Which element is the non- metal? 3)Which element lost electron(s)? 4)Which element gained electron(s) 5)How many of each element is present?

Positive or Negative Charge? When an element LOSES electrons it creates an overall positive charge in that element. When you loose electrons, you end up with more protons (+ charge) than electrons (- charge) overall. This will give you the overall positive charge. When an element GAINS electrons it creates an overall negative charge in that element. When you gain electrons you end up with more electrons (- charge) than protons (+ charge) overall. This will give you the overall negative charge.

Some Qs to Consider... Q1: Take a look at Sodium (Na) on your periodic table. A) Is sodium a metal or a non-metal? B) How many electrons are in the outer shell of sodium? (Use a Lewis dot to help you) C) Is it easier for sodium to loose or gain electrons? D) What charge would it have? Positive or Negative?

Some Qs to consider... Q2: Take a look at Chlorine (Cl) on your periodic table. A) Is chlorine a metal or a non-metal? B) How many electrons are in the outer shell of chlorine? (Use a Lewis dot to help you) C) Is it easier for chlorine to loose or gain electrons? D) What charge would it have? Positive or Negative?

Some Qs to consider... Q3 – If sodium and chlorine were to make an ionic bond of sodium chloride (table salt), who would end up with the positive charge? Who would end up with the negative charge?

Check your Answers...

In general, metals lose electrons to form positive ions. When a positively charged ion comes near a negatively charged ion, they attract each other and form a bond called an ionic bond. An ionic bond will hold the two ions together to form a compound

Octet Rule The tendency of elements to lose or gain electrons to obtain the same number of valence electrons as the nearest noble gas is called the octet rule. In human terms, we can think of atoms wanting to be “happy” and becoming “happy” once they have a complete octet of electrons.

Combining Capacity The number of electrons that an atom must lose or gain to have a complete octet of electrons is called the combining capacity or valence. Sodium loses 1 electron so its combining capacity is +1. When ionic compounds are formed, elements with a positive valence number will combine with elements having a negative valence number. In general terms, metals (families/groups 1 and 2) combine with non-metals (families/groups 16 and 17).

Combining Capacity In the idealized ionic bond, one atom gives up an electron to the other, forming positive and negative ions.