Making Bonding Models

Today We Will… Describe the two main ways elements bond Construct Lewis Dot Diagrams Identify characteristics of Ionic and Compounds Define cation and anion

Bonding Bonding is the sharing or transferring of electrons between elements in order to combine to form molecules or compounds. Bonding is the sharing or transferring of electrons between elements in order to combine to form molecules or compounds.

Types of Bonds Metal + Nonmetal = Ionic (transfer) Nonmetal + Nonmetal = Covalent (share) Metal + Metal = Metallic (sea of electrons)

Bonding possibilities (1) They can try to gain electrons to fill up their last shell. (IONIC) OR (2) They give up electrons and have a filled lower shell. (IONIC) (3) They share a few electrons and have a filled shell. (COVALENT) gain Give share

Lewis Dot Diagrams Discovered by Lewis It is a diagram for each element that depicts that element’s valence electrons Valence Electrons: electrons on the outer shell of an element. This will help us tell how elements will bond!!!

Learning Check A. X would be the electron dot formula for  A. X would be the electron dot formula for 1) Na 2) K 3) Al   B.  X  would be the electron dot formula 1) B 2) N 3) P

How do we know the valence electrons of an element? GROUPS!! Label the valence electrons according to their groups.

Ionic Bond Definition:-bond formed between two ions by the transferring of electrons Ionic bonds only form between a metal and a nonmetal with different electronegativities. Electronegativity- tendency of an atom to attract electrons The more electrons the atom has the more elctronegative it is. Definition: bond formed between two ions by the transfering of electrons Metals become cations (positively charged ions) Nonmetals become anions (negatively charged ions)

Which has the highest electronegativity

Ionic Bonds form Ions Metals become cations (+ charged) Nonmetals become anions (-charged)

Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons C would like to N would like to O would like to Gain 4 electrons Gain 3 electrons Gain 2 electrons

Helium, neon and argon are atoms which do not react with other atoms. Each of these gases has a full outer electron shell (orbit). 10p10n 18p22n 2p2n 4 Ne 20 He 2 10 Ar 40 18 2,8 2,8,8

The Sodium atom has 1 Electron in it’s outer shell. Chemical Bonds.mht Na The Sodium atom has 1 Electron in it’s outer shell. e.c. 2,8,1 Atom + The Sodium loses 1 electron to leave a complete outer shell. It is now a Sodium ion with a charge of 1 + (Na +) e.c. (2,8)+ Ion All Things Science - Ionic and covalent bonding animation.mht

The Chlorine atom has 7 electrons in it’s outer shell. Cl e.c. 2,8,7 Atom - (Cl - ) The Chlorine gains 1 electron to gain a complete outer shell. It is now a Chlorine ion with a charge of 1 - e.c. (2,8,8)- Ion

Oxidation Numbers The plus or minus indicates if electrons were lost or gained. The number indicates how many electrons. Oxidation numbers tell the number of electrons an atom gained or lost when forming the compound. The plus or minus indicates if electrons were lost or gained. The number indicates how many electrons.

Ionic Bond Write the symbol for each element Draw the Electron Dot Diagram Draw an arrow to show the transfer of electrons Make sure the sum of the ions equals zero

Ionic Bond Write the symbol for each element Draw the Electron Dot Diagram Draw an arrow to show the transfer of electrons Make sure the sum of the ions equals zero

Magnesium (Mg) + Fluorine (F) Ionic Bond Magnesium (Mg) + Fluorine (F) Don’t forget to show the oxidation number and the chemical formula.

Ionic Compounds High melting points and boiling points Held together by strong electrostatic forces High melting points and boiling points When melted or dissolved ionic compounds conduct electricity

Covalent Bonding

Today We Will Describe and draw covalent bonding Identify characteristics of covalent compounds Define diatomic atom

Lets Review How many valence electrons makes an atom stable? What is this called? Draw the Lewis Dot Diagram for Sulfur An ionic bond is between a _______ and a ______. An ionic bond forms when electrons are _______ or _______.

Atoms still want to achieve a noble gas configuration. Covalent Bond Atoms still want to achieve a noble gas configuration. Bond formed by sharing electrons Occurs between non metals Results in the formation of a molecule 1. sharing

Covalent Bond Write the symbol for each element Draw the Electron Dot Diagram Rearrange the electrons to pair up with electrons from each atom Draw circles to show sharing of electrons Draw the bond structure for each pair of electrons shared.

Hydrogen (H) + Hydrogen (H) Covalent Bond Hydrogen (H) + Hydrogen (H) H° °H Each hydrogen atom wants to gain one electron to achieve an octet The octet is achieved by each atom sharing the electrons in the middle.

Hydrogen (H) + Hydrogen (H) Covalent Bond Hydrogen (H) + Hydrogen (H) H° °H The pair shared in the middle is called a bonding pair. Since there is only one bonding pair we call this a single bond.

Hydrogen (H) + Hydrogen (H) Covalent Bond Hydrogen (H) + Hydrogen (H) H H Single bonds are represented with a dash.

O Oxygen atoms are highly electronegative. So both atoms want to gain two electrons.

Both electron pairs are shared.

O O 6 valence electrons plus 2 shared electrons = full octet

O O two bonding pairs, making a double bond

Diatomic Atoms Elements that are naturally in molecules with 2 atoms each H O N Cl Br I F

Covalent Compounds Forces between molecules are weak. Usually gas or liquids Low melting point and boiling point No overall electrical charge

Classwork/Homework H2S F2 HF H2O AlF3 MgO NH3 PBr3 CCl4 CS2 CO2 K2S CH4