Chemical Bonding In the next unit, we will discuss how atoms join together to form a chemical bond. There are 3 main types of chemical bonds; Ionic Bonds Metallic Bonds Covalent Bonds

Ionic Bonding Electron Dot Diagrams (Lewis Diagrams) An electron dot diagram shows the number of valence electrons around an atom. The group number tells us how many valence electrons the atom has.

Ionic Bonding Electron dot diagrams Draw the electron dot diagrams of Calcium, Aluminum, and oxygen.

Ionic Bonding Ionic Compounds are substances that form when a cation and an anion attract and ‘stick’ to each other. The force that’ glues’ the ions together is an electrostatic interaction. In other words, opposite charges attract.

Ionic Bonding How do we know the sign and magnitude of the charge an ion will form? Group Charge 1 +1 2 +2 3 +3 4 +4/-4 5 -3 6 -2 7 -1 8 0

Ionic Bonding When a cation and an anion are attracted to each other, an ionic bond has formed.

Ionic Bonding What happens when a calcium ion and a chloride ion come together? What do you think the ratio of cations to anions would be?

Na2O Ionic Bonding Rules for forming and writing ionic compounds; The sum of the positive and negative charges has to equal zero. Ionic compounds are neutral. The cation is written first in the formula. A subscript is used to tell us how many of each atom is in the ionic compound. Na2O

Ionic Bonding Write the chemical formula for the ionic compound that will form from the following elements; Magnesium and sulfur Potassium and nitrogen Barium and bromine Aluminum and oxygen

Ionic Bonding Some ions are polyatomic, they consist of more than one atom. -1 -2 -3 NO2-1 = nitrite SO3-2 = sulfite PO4-3 = phosphate NO3-1 = nitrate SO4-2 = sulfate C2H3O2-1 = acetate

Ionic Bonding Writing chemical formulas of ionic compounds that contain a polyatomic ions; Same ‘rules’ as before but if there is more than one polyatomic ion in the compound, we need to use ( ). NaNO3 Ba(NO3)2 Mg(C2H3O2)2

Ionic Bonding Write the formula of the ionic compound when the following ions bond; Barium ion and the carbonate ion Sodium ion and the hypochlorate ion Magnesium ion and the sulfate ion Aluminum and the hydroxide ion Lithium and the nitrate ion

Naming Ionic Compounds All you have to do is to say the name of the cation, then the root of the anion with the suffix ‘ide’. Na2S = sodium sulfide

Naming Ionic Compounds If the anion or cation is polyatomic, use the name of it without modifying it. Na2SO4 = sodium sulfate

Naming Ionic Compounds If the cation is a trasition metal, write a roman numeral to indicate its charge. CoSO4 = cobalt (II) sulfate

Naming Ionic Compounds Name these ionic compounds; CaF2 = calcium fluoride Mg3N2 = AlPO4 = Ba(NO3)2 =

Naming Ionic Compounds Name these ionic compounds; CuF2 = copper (II) fluoride Mg3N2 = Pb3(PO4)2 = Ba(NO3)2 =

Ionic Compounds Some physical properties; Very high melting point. Very high boiling point. Brittle They have a crystalline structure

Metallic Bonding What happens when two metallic atoms interact? Do they ionize? Do they give away their electrons?

When metallic atoms bond, the metallic nuclei donate their electrons to all of the atoms in the sample. Metallic Bonding

Metallic Bonding This type of bonding between metallic nuclei is called the ‘sea of electrons’ model. It appears as if the metal atoms are floating in an ocean of valence electrons.

Metallic Bonding This type of bonding gives metals some unique properties. Metals are malleable – They can be bent and they will stay in the shape.

Metallic Bonding This type of bonding gives metals some unique properties. Metals are ductile – They can be pulled into long and thin wires.

Metallic Bonding An alloy is a mixture of metals. Some common alloys are; Brass (Cu and Zn)

Metallic Bonding An alloy is a mixture of metals. Some common alloys are; Bronze (Cu and Pb)

Metallic Bonding An alloy is a mixture of metals. Some common alloys are; 14 carat gold (Au and Ni)

Metallic Bonding An alloy is a mixture of metals. Some common alloys are; 10 carat gold (Au and Ni) (But even more Ni than 14 carat gold.)

Metallic Bonding An alloy is a mixture of metals. Pure Gold (not an alloy); 24 carat gold (100 % Au)

Covalent compounds A covalent compound consists of two or more nonmetals. They are able to bond together by sharing their valence electrons.

Covalent compounds Atoms will share 1, 2, or 3 pairs of electrons so that each valence level has a stable octet. This sharing of electrons is the bond that keeps the atoms together.

Covalent compounds Single covalent bond – Atoms share 1 pair of electrons. Double covalent bond – Atoms share 2 pairs of electrons. Triple covalent bond – Atoms share 3 pairs of electrons.

Covalent compounds We can determine how many pairs of electrons are shared by drawing an Electron-Dot Diagram.

Covalent compounds Steps for drawing Electron-Dot Diagrams; 1.) Add up the number of valence electrons that each atom brings to the compound. 2.) Arrange the atoms in the compound next to each other. If there are more than two atoms in the compound, arrange them symetrically with the atom that was listed first as the central atom. 3.) Place 1 pair of electrons between each atom that will be bonded together.

Covalent compounds Steps for drawing Electron-Dot Diagrams (cont.); 4.) Use the remaining electrons to satify the octet rule for each element in the compound. 5.) If there are not enough electrons, place another pair of electrons between 2 atoms. 6.) If there are extra electrons, place them on the central atom, even if it already has 8 electrons.

Covalent compounds Electron-Dot Diagrams; Draw the EDD for chlorine gas (Cl2). Each atom brings 7 valence electrons for a total of 14 electrons. Bond the chorine atoms with a single pair of electrons. Now there are 12 electrons left. Cl:Cl

Covalent compounds Electron-Dot Diagrams; Place 6 more electrons around each chlorine atom. The Octet Rule is satisfied for both atoms. Cl:Cl

Electron-Dot Diagrams; Draw the EDD for bromine (Br2). Covalent compounds Electron-Dot Diagrams; Draw the EDD for bromine (Br2).

Electron-Dot Diagrams; Draw the EDD for carbon tetrachlorde (CCl4). Covalent compounds Electron-Dot Diagrams; Draw the EDD for carbon tetrachlorde (CCl4).

Electron-Dot Diagrams; Draw the EDD for Oxygen gas (O2). Covalent compounds Electron-Dot Diagrams; Draw the EDD for Oxygen gas (O2).

Electron-Dot Diagrams; Draw the EDD for Nitrogen gas (N2). Covalent compounds Electron-Dot Diagrams; Draw the EDD for Nitrogen gas (N2).

Electron-Dot Diagrams; Draw the EDD for Carbon monoxide (CO). Covalent compounds Electron-Dot Diagrams; Draw the EDD for Carbon monoxide (CO).

Electron-Dot Diagrams; Draw the EDD for carbon dioxide (CO2). Covalent compounds Electron-Dot Diagrams; Draw the EDD for carbon dioxide (CO2).

Covalent compounds Exceptions in drawing Electron-Dot Diagrams; Just like everything else in Chemistry, there are exceptions to the Octet Rule. Hydrogen – Stable with only 2 valence electrons. Boron – Stable with 6 valence electrons. Sulfur and Phosphorous – Stable with 8, 10, or 12 valence electrons.

Covalent compounds Exceptions in drawing Electron-Dot Diagrams; Draw the EDD of Hydrogen Chloride (HCl).

Covalent compounds Exceptions in drawing Electron-Dot Diagrams; Draw the EDD of boron trifluoride (BF3).

Covalent compounds Exceptions in drawing Electron-Dot Diagrams; Draw the EDD of phophorous pentachloride (PCl5).

Draw the electron dot diagram for the ammonium ion. Covalent compounds Draw the electron dot diagram for the ammonium ion.

Covalent compounds Resonant Structures Resonant structures are multiple ways of drawing an EDD for a molecule. The nitrate ion, NO3-1, has three different ways to draw its dot diagram;

Covalent compounds Resonant Structures Which molecule has resosnant structures, SO3 or SO3-2?

Covalent compounds Coodinate Covalent Bonds A coordinate covalent bond forms when one atom donates both electrons that are used to form a covalent bond.

Covalent Compounds Naming Covalent Compounds Prefixes have to be used since different compounds can have different ratios of the same elements. mono = 1, di = 2, tri = 3, tetra = 4, penta = 5, hexa = 6, hepta = 7, octa = 8, nona = 9, and deca = 10

Covalent Compounds Naming Covalent Compounds Use a prefix to indicate the number of atoms of each element in the covalent compound and add the suffix ‘ide’ to the name of the last element. N2O4 = dinitrogen tetroxide P2O10 = diphophorous decoxide CO2 = carbon dioxide * CO = carbon monoxide * * If there is only one of the first element, don’t use a prefix. It is implied that there is only 1 atom in the compound.

Covalent Compounds Naming Covalent Compounds Name these covalent compounds; H2O CCl4 CS2 S2O6

Covalent Compounds Naming Covalent Compounds There is a special type of covalent compounds called acids. An acid will always contain hydrogen. The hydrogen will be listed first. Acids have a different naming system.

Covalent Compounds Naming Covalent Compounds Naming Acids that do not contain oxygen; Use the prefix ‘hydro’ on the name of the second element with the suffix ‘ic’. HCl = hydrochloric acid HF = hydrofluoric acid H2S = hydrosulfic acid HBr = hydrobromic acid

Covalent Compounds Naming Covalent Compounds Naming Acids that contain oxygen; If the anion ends in ‘ate’, then use the suffix ‘ic’ on the name of the anion. H2SO4 = sufuric acid If the anion ends in ‘ite’, then use the suffix ‘ous’ on the name of the anion. H2SO3 = sulfurous acid

Covalent Compounds Naming Covalent Compounds Name these acids; HI HCl H3PO4 H2C2O4 HC2H3O2

Covalent Compounds VSEPR Theory Valence Shell Electron Pair Repulsions Bonding electrons and lone pairs of electrons will repel themselves so that they will separate by the maximum distance possible.

Covalent Compounds VSEPR Theory Valence Shell Electron Pair Repulsions The shape of a molecule is determined by these repulsive forces.

Covalent Compounds VSEPR Theory Valence Shell Electron Pair Repulsions Linear Shape A molecule consisting of just 2 atoms will always be linear. A molecule with 3 atoms can be linear if there are no lone pairs of electrons on the central atom.

Covalent Compounds VSEPR Theory Valence Shell Electron Pair Repulsions Bent Shape A molecule that has 3 atoms but there is a lone pair(s) of electrons on the central atom.

Covalent Compounds VSEPR Theory Valence Shell Electron Pair Repulsions Trigonal Planar Shape A molecule that has 4 atoms with no lone pairs on the central atom.

Covalent Compounds VSEPR Theory Valence Shell Electron Pair Repulsions Trigonal Pyramidal Shape A molecule that has 4 atoms with a lone pair of electrons on the central atom.

Covalent Compounds VSEPR Theory Valence Shell Electron Pair Repulsions Tetrahedral Shape A molecule that has 5 atoms with no lone pairs of electrons on the central atom.

Covalent Compounds VSEPR Theory Valence Shell Electron Pair Repulsions Trigonal Bipyrimidal Shape A molecule that has 5 atoms with no lone pairs of electrons on the central atom.

Covalent Compounds Bond Polarity Polar – having two distinct ends. Sometimes, there is an unequal sharing of the electrons that make up a covalent bond. As a result, the bonding electrons can spend more time with atom compared to the other one.

Covalent Compounds Bond Polarity The atom with the higher electronegativity value will have the bonding electrons most of the time. The atom with the higher electronegativity will have a partial negative charge (δ-).

Covalent Compounds Bond Polarity The atom with the lower value of electronegativity will appear to have a positive charge (δ+).

Covalent Compounds Bond Polarity If two bonding atoms have the same electronegativity, the bond will not appear to be polar.

O = C = O Covalent Compounds δ- δ+ δ- Bond Polarity When determining if a molecule is polar or nonpolar, you must analyze the entire molecule and consider its shape. CO2 is nonpolar. δ- δ+ δ- O = C = O

Covalent Compounds Bond Polarity When determining if a molecule is polar or nonpolar, you must analyze the entire molecule and consider its shape. CCl4 is nonpolar.

Covalent Compounds Bond Polarity When determining if a molecule is polar or nonpolar, you must analyze the entire molecule and consider its shape. H2O is polar.

Covalent Compounds Bond Polarity When determining if a molecule is polar or nonpolar, you must analyze the entire molecule and consider its shape. HCl is polar.

Covalent Compounds Bond Polarity When determining if a molecule is polar or nonpolar, you must analyze the entire molecule and consider its shape. Is NH3 polar or nonpolar?

Covalent Compounds Bond Polarity Electronegativity Table

Covalent Compounds Are the following compounds polar or non polar? PH3: SO3: H2S: I2: CS2:

Covalent Compounds Intermolecular Forces Forces of attraction between 2 or more other molecules in a substance.

Covalent Compounds Intermolecular Forces 3 types: London Dispersion Forces (weakest), Dipole-Dipole, and Hydrogen Bonding (strongest).

Covalent Compounds Intermolecular Forces London Dispersion Forces: Weak forces of attractions caused by the attraction between the protons in one molecules and the electrons in another molecule.

Covalent Compounds Intermolecular Forces Dipole - Dipole Forces: Weak forces of attractions caused by the attraction between the oppositely charged poles of two or more molecules.

Covalent Compounds Intermolecular Forces Hydrogen Bonding: Forces of attractions between a hydrogen atom of one molecule and a fluorine, oxygen, or nitrogen, of another molecule.

Covalent Compounds Intermolecular Forces Hydrogen Bonding: Forces of attractions between a hydrogen atom of one molecule and a fluorine, oxygen, or nitrogen, of another molecule.