using information from the periodic table. when atoms combine the goal of every atom is to become...

Using Information

From the Periodic Table

When Atoms CombineThe goal of every atom is to become stableThis can be achieved by creating bonds with other elements to completely fill outer electron shells

Atoms that are unstable—that is, atoms in which the outer electron level is not full—will react readily with atoms that can fill their outer

electron level.

Determining How Atoms Will React All elements exhibit an electron configuration. Those that have stable configurations are less likely to react.

-How do you determine if the atom is stable or unstable? This can be completed using an electron dot diagram.

The symbol represents the nucleus The dots represent the number of valence electrons

Let’s Practice

1. Determine the group number of the element.

2. Write the element symbol

3. Place dots (valence e-) in a clockwise position until you have reached 8.. (octet rule)

4. Do not place more than one electron at a time. (exceptions are H and He)

Achieving Stability

Although the goal is to become stable; all atoms will not be based on their electron configuration.

Some elements achieve this by transferring/sharing electrons, thus creating chemical bonds. 2 Major Types of Chemical Bonds

Ionic BondsCovalent Bonds

What is an Ion?Remember: Atoms are electrically neutral because????

An atom that carries an electrical charge is called an ion

If the atom loses electrons, the atom becomes positively charged –it becomes a cation

If the atom gains electrons, the atom becomes negatively charged- it becomes an anion

Ion Formation

All of the elements in Group I have one electron in their outermost energy level.

All of these elements can lose that one valence electron.

These atoms become cations with a positive one charge.

+2+1

+3 -3 -2 -1

How can electrons travel? Recall:

As electrons move from one energy level to another they gain and lose energy.

Going up an energy level = energy gained Going down an energy level= energy lost

Ionization energy is the amount of energy used or required to remove an electron.

Using the periodic table….. This energy increases across the period Decreases from the top to the bottom of a

group

Ionic Bonds metallic atoms tend to lose electrons- becoming cations Nonmetallic atoms tend to gain electrons to become

negatively charged ions which are called anions. These oppositely charged cations and anions are

attracted to one another because of their opposite charges.

A chemical bond that occurs when Electrons are transferred Between cations and anions Metals and nonmetals High melting and boiling points Conduct electricity when melted or dissolved in water Many are soluble in water but not in non-polar liquid Creates salts

Ex: Sodium( Na) and Chlorine (Cl) create NaCl (table salt)

Positive Ion (Cation) Formation

Negative Ion (Anion) Formation

• Na has one valence electron. • It loses it to Chlorine. • Na now has a filled valence shell.

(an octet)• Becomes positive one in charge • Chlorine has seven valence

electrons. • It gains one electron from Na. • Chlorine now has filled octet. • Chlorine has a negative one

charge. (Chloride ion)• Na+1 attracts Cl-1 and forms the

ionic bond.

Covalent Bonds

involve the sharing of a pair of valence electrons by two atoms

Occurs between nonmetals Can be polar(unequal pairing) or nonpolar(equal

pairing) Low melting points Can be solid, liquid, or gas at room temperature. Do not conduct electricity; non electrolytes

Naming Chemical Compounds and Balancing

Equations

Chemical ReactionsA chemical reaction changes one set of chemicals into another set of chemicals.

Elements or compounds that enter into a chemical reaction are known as reactants.

CO2 + H2O H2CO3

(Reactants)

Chemical Reaction

The elements or compounds produced by a chemical reaction are known as products.

CO2 + H2O H2CO3

(Product)

All chemical reactions can be placed into one of five categories. Here they are, in no particular order:

1) Combustion: A combustion reaction is when oxygen combines with another compound to form water and carbon dioxide. These reactions are exothermic, meaning they produce heat. An example of this kind of reaction is the burning of napthalene:

C10H8 + 12 O2 ---> 10 CO2 + 4 H2O

2) Synthesis: A synthesis reaction is when two or more simple compounds combine to form a more complicated one. These reactions come in the general form of:

A + B ---> AB One example of a synthesis reaction is the

combination of iron and sulfur to form iron (II) sulfide:

8 Fe + S8 ---> 8 FeS

3) Decomposition: A decomposition reaction is the opposite of a synthesis reaction - a complex molecule breaks down to make simpler ones. These reactions come in the general form:

AB ---> A + B One example of a decomposition reaction is

the electrolysis of water to make oxygen and hydrogen gas:

2 H2O ---> 2 H2 + O2

4) Single displacement: This is when one element trades places with another element in a compound. These reactions come in the general form of:

A + BC ---> AC + B One example of a single displacement reaction

is when magnesium replaces hydrogen in water to make magnesium hydroxide and hydrogen gas:

Mg + 2 H2O ---> Mg(OH)2 + H2

5) Double displacement: This is when the anions and cations of two different molecules switch places, forming two entirely different compounds. These reactions are in the general form:

AB + CD ---> AD + CBOne example of a double

displacement reaction is the reaction of lead (II) nitrate with potassium iodide to form lead (II) iodide and potassium nitrate:

Pb(NO3)2 + 2 KI ---> PbI2 + 2 KNO3

Follow this series of questions. When you can answer "yes" to a question, then stop!

1) Does your reaction have oxygen as one of it's reactants and carbon dioxide and water as products? If yes, then it's a combustion reaction

2) Does your reaction have two (or more) chemicals combining to form one chemical? If yes, then it's a synthesis reaction

3) Does your reaction have one large molecule falling apart to make several small ones? If yes, then it's a decomposition reaction

4) Does your reaction have any molecules that contain only one element? If yes, then it's a single displacement reaction

5) Does your reaction have water as one of the products? If yes, then it's an acid-base reaction

6) If you haven't answered "yes" to any of the questions above, then you've got a double displacement reaction

Try These Now!

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Naming Ionic Compounds with Two Elements

To name a compound that contains two elements,

• identify the cation and anion.

• name the cation first followed by the name of the anion.

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Learning CheckComplete the names of the following ions. Ba2+ Al3+ K+

_________ __________ _________

N3 O2 F

_________ __________ _________

P3 S2 Cl _________ __________ _________

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Solution

Ba2+ Al3+ K+

barium aluminum potassium

N3 O2 F

nitride oxide fluoride

P3 S2 Cl phosphide sulfide chloride

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Examples of Ionic Compounds with Two Elements

Formula Ions Name

cation anion

NaCl Na+ Cl- sodium chlorideK2S K+ S2- potassium sulfideMgO Mg2+ O2- magnesium oxideCaI2 Ca2+ I- calcium iodideAl2O3 Al3+ O2- aluminum oxide

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Learning CheckWrite the names of the following compounds.

1) CaO ___________

2) KBr ___________

3) Al2O3 ___________

4) MgCl2 ___________

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Learning Check

Write the formulas and names for compounds of the following ions: Br− S2− N3−

Na+

Al3+

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Solution

Br− S2− N3−

Na+

Al3+

NaBrsodium bromide

Na2Ssodium sulfide

Na3Nsodium nitride

AlBr3

aluminum bromide

Al2S3

aluminum sulfide

AlNaluminum nitride

using information from the periodic table. when atoms combine the goal of every atom is to become...

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