Types of Bonding Lab Wrap Up

What Do The Formulas Mean? Describe what elements make up the compound Describe what elements make up the compound Also describes how many of each type of atom there are in the compound Also describes how many of each type of atom there are in the compound C2H2F4C2H2F4C2H2F4C2H2F4 What Elements Are Present How many of each there are

More Complicated Formulae Formulae may have the same element more than once. This indicates something about the chemical structure, which we will learn about in Unit 5. For example: NH 4 OH

More Complicated Formulae Formulae may have parentheses: For example: Al(NO 3 ) 3 The number outside the parentheses applies to each of the atoms in the parentheses

How Many of Each Atom Are In A Formula? C3H8OC3H8OC3H8OC3H8O MgSO 4 Ca(OH) 2 NH 4 NO 3 Mg 3 (PO 4 ) 2 Fe(NO 3 ) 3

What Does Conductivity Mean? How well a solution conducts electricity How well a solution conducts electricity What do you need to conduct electricity? What do you need to conduct electricity? To conduct electricity you need moving charges To conduct electricity you need moving charges Things with high conductivities have lots of things with charges that can move. Things with high conductivities have lots of things with charges that can move.

A Few Conductivity Terms Electrolyte – a compound that conducts electricity when dissolved in water. Electrolyte – a compound that conducts electricity when dissolved in water. Strong electrolyte – conducts electricity well Strong electrolyte – conducts electricity well Weak electrolyte – conducts electricity slightly Weak electrolyte – conducts electricity slightly Non-electrolyte – does not conduct electricity Non-electrolyte – does not conduct electricity

What does the Melting Point mean? When a compound changes states some of the forces that attract the various pieces together are broken. When a compound changes states some of the forces that attract the various pieces together are broken. Low melting points indicate weak attractions between the little bits. Low melting points indicate weak attractions between the little bits.

What Does Appearance Mean? Regular Shapes are very important in science Regular Shapes are very important in science A Regular Shape at the visible level means that there is a very Regular Shape at the microscopic and atomic levels. A Regular Shape at the visible level means that there is a very Regular Shape at the microscopic and atomic levels.

Types of Chemical Bonding What Makes Salt, Aspirin, and Zinc Have Such Different Properties?

Things Like Sodium Chloride High Melting Points High Melting Points Do Not Conduct Electricity in Solid Form Do Not Conduct Electricity in Solid Form Conduct Electricity in Solution Conduct Electricity in Solution Have a regular shape Have a regular shape Made from a metal and a nonmetal (ex. NaCl) Made from a metal and a nonmetal (ex. NaCl)

Things Like Sodium Chloride Metal loses electrons while nonmetal gains electrons (Na + and Cl - ) Metal loses electrons while nonmetal gains electrons (Na + and Cl - ) Make ions = charged things Make ions = charged things Opposite Charges Attract Opposite Charges Attract Have a regular crystal structure Have a regular crystal structure Crystals come from a repeating pattern of ions. Crystals come from a repeating pattern of ions.

Things Like Sodium Chloride Pattern of ions repeats billions of times in a single crystal = CRYSTAL LATTICE Pattern of ions repeats billions of times in a single crystal = CRYSTAL LATTICE Has no specific number of atoms in crystal so we use an empirical formula Has no specific number of atoms in crystal so we use an empirical formula Empirical formula - Lowest whole number ratio of atoms Empirical formula - Lowest whole number ratio of atoms Call these compounds “salts” Call these compounds “salts”

Things Like Sodium Chloride When melted, ions are freed from the crystal lattice structure When melted, ions are freed from the crystal lattice structure Melting requires breaking the bonds holding the compound together Melting requires breaking the bonds holding the compound together Bonds are strong Bonds are strong Therefore, melting point is high. Therefore, melting point is high.

IONIC BONDING Bonding between ions Atoms give and take electrons Transfer electrons Things like Salt

Things Like Aspirin Low Melting Points Low Melting Points Do Not Conduct Electricity in Solid Form Do Not Conduct Electricity in Solid Form Most Do Not conduct electricity in aqueous solution (some compounds in this category do a little bit) Most Do Not conduct electricity in aqueous solution (some compounds in this category do a little bit) Have an irregular shape Have an irregular shape Made from all nonmetals (ex. C 9 H 8 O 4 ) Made from all nonmetals (ex. C 9 H 8 O 4 )

Things Like Aspirin Atoms share pairs of electrons between each other (potluck dinner) Atoms share pairs of electrons between each other (potluck dinner) Shared electrons hold the atoms together Shared electrons hold the atoms together

Things Like Aspirin Smallest units have a distinct beginning and a distinct end = MOLECULE Smallest units have a distinct beginning and a distinct end = MOLECULE Has a specific number of atoms in the molecule (ex. C 9 H 8 O 4 ) Has a specific number of atoms in the molecule (ex. C 9 H 8 O 4 )

Things Like Aspirin One line = SINGLE BOND = 2 electrons One line = SINGLE BOND = 2 electrons Two lines = DOUBLE BOND = 4 electrons Two lines = DOUBLE BOND = 4 electrons Three lines = TRIPLE BOND = 6 electrons Three lines = TRIPLE BOND = 6 electrons

Things Like Aspirin When melted, bonds between atoms do NOT break When melted, bonds between atoms do NOT break Instead, attractive forces between molecules break. Instead, attractive forces between molecules break. Intermolecular Forces Intermolecular Forces Intermolecular forces are weak compared to bonds. Intermolecular forces are weak compared to bonds. Melting point is low. Melting point is low.

COVALENT BONDING Atoms Share Electrons to Make a Compound Things like Aspirin

Things Like Zinc High Melting Points High Melting Points DO conduct electricity in the solid state DO conduct electricity in the solid state Don’t form aqueous solutions Don’t form aqueous solutions Have irregular shape but are malleable Have irregular shape but are malleable Made from all metals (ex. Brass – a mixture of copper and zinc) Made from all metals (ex. Brass – a mixture of copper and zinc)

Metals Overlap of the electron cloud of the metal atoms Overlap of the electron cloud of the metal atoms Creates metal ions Creates metal ions Electrons move freely through the whole piece of metal Electrons move freely through the whole piece of metal “Sea of Electrons” “Sea of Electrons”

Things Like Zinc When metals melt, some of the attractions from the sea of electrons are broken. When metals melt, some of the attractions from the sea of electrons are broken. Bonds are broken. Bonds are broken. Melting point is high. Melting point is high.

Things Like Zinc Because of the sea of electrons metals: Can have its shape changed = MALLEABLE Can have its shape changed = MALLEABLE Can be pulled into wire = DUCTILE Can be pulled into wire = DUCTILE Are shiny = LUSTEROUS Are shiny = LUSTEROUS

METALLIC BONDING A Sea of Electron Glue Holds Atoms Together Delocalized Electrons Things like Zinc