Chapter 4: The Structure of Matter

Section 1: Compounds & Molecules What are compounds? When elements combine to form a compound, the compound has properties different from the elements that make it. NaCl

Chemical Bonds Chemical bonds distinguish compounds from mixtures. Mixtures are made of _________substances that are placed together. Each substance in the mixture keeps its own properties. Chemical Bonds are the attractive forces that hold different atoms together in a compound.

A compound always has the same chemical formula. Ex. Water _________ Table Sugar C12 H22 O11 Glucose __________ A Chemical Formula shows the types & numbers of atoms in the compound Compounds are always made of the same elements in the same proportions.

Chemical Structure shows the bonding within a compound The arrangement of atoms within a compound determine many of its properties. Example: H2O Bond Length: The avg. distance between the nuclei of 2 bonded atoms Bond Angles: The angle formed by 2 bonds of the same atom.

Some structures are made of bonded ions. Example: NaCl A repeating network connected by strong bonds Positive Na bonded to Negative Cl The strong attractions between oppositely charged ions give NaCl high melting & boiling points

Some compounds are made of molecules Example: “Air” Air contains Nitrogen, Oxygen, & Carbon Dioxide. All 3 substances are made of molecules Atoms within each molecule are strongly bonded. The attraction between the different molecules are not as strong

Chapter 4 Section 2: Ionic & Covalent Bonds The outermost energy levels of a bonded atom is full of ____________. Atoms bond when their __________ electrons interact. Generally, atoms join to form bonds so each atom will have a full outer energy level.

Ionic Bonds Form between oppositely charged ions Na+ Cl- Metals form _______________ charged ions. Nonmetals form____________ charged ions. Ionic Bonds are formed by the ________of electrons.

Properties of Ionic Compounds Will form between metals & nonmetals When melted or dissolved in water, ionic compounds conduct ___________. Electric current is moving charges Solid ionic compounds do not conduct electricity because their particles have very little movement.

Metallic Bonds Electrons move freely between metal atoms A Metallic Bond is a bond formed by the attraction between positively charged metal ions & the elements around them In metallic bonds the outer levels overlap and electrons move freely from atom to atom.

Covalent Bonds Electrons are _________ between bonded atoms. Often formed between nonmetals Most covalent bonds have a ______ melting point Due to weaker bonds between atoms. Atoms are free to move in compound & do not conduct electricity (not charged)

Polar Covalent Bonds When 2 different atoms share electrons, they are not shared ___________. A Polar Covalent Bond is formed by the unequal sharing of electrons Electrons are more attracted to the elements located on the far right (____________)

Polyatomic Ions Compounds that have both ________ & ___________ bonds are polyatomic Example: Baking Soda & Ammonium nitrate Parentheses group the atoms of a polyatomic ion. (NH4)2SO4 Indicate when elements act as a single ion. The charge applies to the whole ion

Chapter 4 Section 3 Compound names & formulas Compound names & formulas are related Compound names reflect the elements which they are made of.

Group Charges Group 1 = 1+ Group 2 = 2+ Groups 3-12 (Tend to have more than one charge) Can lose valence electrons as well as lower level electrons Group 13 = 3+ Group 14 = 2+ or 4+

Group Charges Group 15 = 3- Group 16 = 2- Group 17 = 1- Group 18 = 0 (stable/noble gases) Lanthanides = 3+ Actinides = 3+ or 4+

Naming Ionic Compounds Ionic Compounds are formed between anions & cations. (nonmetals & metals) When atoms lose electrons they are written with a_________ charge Ex. Sodium loses one e- (Na+) Calcium loses two e- (Ca 2+) Table 4-4 shows common names & symbols for cations.

Most anions have the same charge as elements in their same _________. An anion (________) that is made of one element has a name similar to the element Example: Flourine becomes a flouride ion when combined with a cation. Table 4-5 (common anions) Most anions have the same charge as elements in their same _________.

Ex. Calcium Chloride Calcium has a charge of ______ Chlorine has a charge of ______ How can you balance the compound? CaCl2

How can you determine the charge of a transition metal? Like all compounds, ionic compounds have a total charge of ________. This means the total positive charge of the cation must equal the total negative charge of the _________. Example: An Oxide ion, O2- has a charge of _____. 3 ions would have a total charge of ______.

Some cation names must show their charge Example: FeO & Fe2O3 Iron is a transition metal which can form many cations each with a different charge. (table 4-6) The cation must be followed by a Roman Numeral in parentheses Example Fe2O3 iron(III)oxide

Writing Formulas For Ionic Compounds You can determine the formula for a chemical compound by looking at its name Example: Aluminum Flouride

Practice Problems Lithium Oxide Beryllium Chloride 3. Titanium (III) nitride 4. Cobalt (III) Hydroxide

Practice Problems 1. Magnesium Bromide 3. Lithium Nitride 2. Rubidium Oxide 4. Potassium Sulfate

Ions will end in what suffix? What is the charge of a cation? What is the charge of an anion? Balanced Chemical compounds have an overall charge of what? What is the charge of group one? What is the charge of group 18? What is the charge of group 2?

Naming Covalent Compounds Covalent compounds are named using different rules. Numerical Prefixes are used to name covalent compounds of 2 elements Tell how many atoms of each element are in the compound (Table 4-7) Example: Triflouride Dinitrogen tetroxide

Numerical Prefixes (pg. 126) Mono- 2 Di- 3 Tri- 4 Tetra- 5 Penta- 6 Hexa- 7 Hepta- 8 Octa- 9 Nona- 10 Deca-

Practice  MnF3 FeO Titanium(III) Sulfide

Practice  1. Diarsenic Pentoxide 2. Carbon Dioxide 3. Tetraphosphorus Trisulfide 4. Phosphorus Hexoxide

Empirical Formula A compound’s simplest formula is its empirical formula. Tells the smallest whole-number ratio of atoms in the compound Example: H20 2:1 Scientists have to analyze unknown compounds to determine their empirical formula.

An unknown compound weighs 142 g. It contains the O & P An unknown compound weighs 142 g. It contains the O & P. It has 62 g of P & 80 g of O. How can you calculate its empirical formula?

Convert the mass in to moles! What is the conversion unit for converting mass into moles? How many moles of P have a mass of 62g? How many moles of O have a mass of 80g?

Different compounds can have the same empirical formula. Example: Formaldehyde, Glucose, & Acetic Acid (Vinegar) all have the same empirical formula = CH2O What formula can be used to determine the difference between similar compounds? Its Molecular Formula!!

Molecular Formulas are determined from empirical formulas Molecular formulas show the actual numbers of atoms in one molecule of a compound. Covalent Compounds have both empirical & molecular formulas.

Chapter 4 Section 4 Organic & Biochemical Compounds An Organic Compound is a covalently bonded compound made of molecules In a covalent bond electrons are _________. In an ionic bond electrons are __________.

Organic Compounds contain __________. Almost always contain hydrogen May contain oxygen, nitrogen, sulfur, & phosphorus

Carbon atoms form 4 covalent bonds in organic compounds When a compound is made only of carbon & hydrogen it is a hydrocarbon Example: methane (C-H) Carbon can also form double bonds or triple bonds with other atoms

Alkanes have single covalent bonds & names end with -ane Alkanes are hydrocarbons that have only single covalent bonds Example: Methane C-H (simplest alkane) Alkanes can also have bonds between carbons (C-C) Example: Ethane C2H6 Each Carbon atom bond with 4 other atoms

Arrangement of carbon atoms When 3 or more carbon atoms are bonded they do not always line up in a row. (structurally) When the atoms DO line up they are named “normal alkanes” ( n- alkane)

Alkanes with more than 3 carbon atoms have many possible arrangements. They can be Branched, Unbranched, or form Rings (Figure 4-26)

Alkane formulas Except for cyclic alkanes, the chemical formula always has a special pattern The # for Hydrogen atoms is 2 more than twice the number of carbon atoms. Example: C3 H8

Alkenes have Double carbon- carbon bonds (-ene) Alkenes are hydrocarbons Different from alkanes because they have at least one double covalent bond between carbon atoms C=C

Alkenes Examples: Ethylene C2H4 Propylene C3H6

Alcohols have –OH groups end in “ -ol ” Alcohols organic compounds are made of Oxygen as well as hydrogen & carbon Alcohols have hydroxyl, or –OH groups Example: Ethanol CH3CH2OH

Alcohol molecules behave similarly to water molecules Neighboring molecules are attracted to one another Properties of adhesion & cohesion Alcohols are liquid at room temperature but have very high boiling points

Polymers Large molecules made of smaller subunits Many polymers have repeating subunits Example: polyethene Polymers exist naturally & can be synthetic Natural: rubber, wood, cotton, wool, starch, protein, DNA Synthetic: Plastics or Fibers

A Polymer’s elasticity is determined by its structure (Similar to a chain) When the monomers are liked together the polymer becomes elastic.

Biochemical Compounds Naturally occurring organic compounds that are very important to living things. Example: Carbohydrates, Proteins, & DNA

1. H7Cl2 _________________________________ 2. C4Br6 __________________________________ 3. P3O10 _________________________________ 5.N5F8 ________________________________

Naming Ionic Practice: __________________________ CaCl2 ________________________ K2O ___________________________ MgO

Chapter 4 Vocabulary Quiz

1. A compound made only of hydrogen and carbon

2. The simplest chemical formula of a compound that tells the smallest whole number ratio of atoms in the compound

3. Any one of 20 different naturally occurring organic molecules that combine to form proteins

4. Any organic compound that is made of carbon, hydrogen, & oxygen and that provides nutrients to the cells of living things

5. Any covalently bonded compound that contains carbon

6. A biological polymer made of bonded amino acids

7. A large organic molecule made of many smaller bonded units

8. Hydrocarbons that have only single covalent bonds

9. A Chemical Formula that reports the actual numbers of atoms in one molecule of a compound

10. A bond formed by the attraction between oppositely charged ions