Unit 2 Chemistry Study Guide: Matter , Nomenclature & Bonding

Normal Boiling Point/ Normal Melting Point

"Normal" boiling point/melting point occurs at Standard Temperature and Pressure (STP). T = 273.15 K °Celcius + 273 = Kelvin (K) P = 1 atmosphere (atm) Remember 273

Polyatomic Ion

*An ion made from 2 or more atoms*

Mixtures

*Can be composed of 2 or more elements OR compounds* *NOT combined in a fixed ratio* *Can be physically separated*!

Chemical Properties

*Can be observed during a chemical reaction; describes a material's ability to undergo a chemical change* Examples: Ability to... Brown Tarnish Rust Oxidize Combust (flammability) Spoil

Chemical Formula

*Combination of atomic symbols that represents the atoms in a compound in their fixed ratios*.

Matter

Anything that has *Mass* *Volume*

Relationship between temperature & phases

As temperature rises, and pressure is held constant, KE increases and causes: solid---liquid---gas

Why do atoms bond?

Atoms bond because they try to get a *full set* of valence electrons. This makes them more *stable*.

Ionic & Covalent Bond Review

Atoms form bonds to achieve noble gas configuration Ionic Bonds *Metals and nonmetals* Electrons are *transferred* between atoms Covalent Bonds Between *nonmetals* Result from *sharing* of electrons

Chemical Bonds

Attraction between two or more atoms Interaction between outermost valence electrons

Bonding Study Guide

Bonding Study Guide

Ternary Ionic Compound

Contains at least one polyatomic ion These always have a metal unless you have a positive polyatomic (ammonium). If you have more than one polyatomic attached, you need parentheses around your polyatomic! For example Ba(OH)2

Binary Ionic Compound

Contains only *2* elements Always contain a metal and a non-metal. The metal comes first The name stays the same The non-metal comes second Use the non-metal stem and add ide. For example, fluorine becomes fluoride

Condensation

Decrease temperature Decrease surface area opposite of Evaporation

Extensive Properties: Matter does matter

Depends on the *amount* of matter Examples: Mass Length Volume Weight

Forming Ionic Compounds

Electrons are *transferred* and the *oppositely* charged ions are attracted to each other. The charge of the compound is *neutral*:

Ionic Compounds

Electrons go from metals to nonmetals Attraction between + ions and - ions Forms an ionic compound electron transfer results in *metal ----- nonmetal --- ion+ ion*- # of Electrons lost = *electrons gained*

Deposition

Example: Snow, Frost, Hydrogen sulfide gas depositing sulfur around vents in Yellowstone

Ionic Compounds

High melting points and are brittle *Electrolytes* —any compound that conducts electricity when melted or when dissolved in water. Have a *crystalline structure* (crystal) - regular, repeating arrangement of atoms, ions, or molecules Solid ionic compounds (crystals) do not conduct electricity because the ions are fixed in shape. They must be dissolved in water first.

Alloys

Homogeneous mixture of metals Examples: Bronze - Cu; Sn White Gold - Au; Ni Pewter - Sn/Cu/Sb/Bi/Pb Stainless Steel - Fe/Cr Amalgam - An alloy Containing Mercury. (Hg) Braces

Centrifuge

Machine that spins a sample very quickly so that components with different densities will separate *Type of Mixture(s) Separated* - Both hetero- & homogeneous

Molecular/Covalent Compounds

Made from *2 atoms* that are *both nonmentals* Low melting and boiling points Don't conduct electricity Less soluble in water than ionic compounds

Diatomic Molecule

Made from *2* atoms of the same element ex: N2, Cl2, H2 7 Diatomic elements: H2 N2 O2 F2 Cl2 Br2 I2 Remember: "HONClBrIF" Go to element #7 and make a #7. Just don't forget Hydrogen!

Ionic Compounds

Made from 2 ions, one with a positive charge & the other with a negative charge. The positive ion is always written first. The total charge of the compound must be zero. The possible ion combinations are: - A metal & a nonmetal - A polyatomic ion & a nonmetal _ A metal & a polyatomic ion - 2 polyatomic ions *Metal & Non-metal* Binary ionic compound- contains only 2 elements. Rules for Writing Formulas Write symbols with the charges. Metal is written first. Determine how many of each ion is necessary to make the charge zero. Represent the number of each with subscripts. Simplify

Melting Vs. Freezing

Melting occurs at a specific temperature called the Melting Point. - KE is INCREASING. Freezing occurs at a specific temperature called the Freezing Point. - KE is DECREASING.

Nomenclature

Nomenclature

The two main types of matter are

Pure Substances (Definte Composition) Mixtures

Covalent Bonds

Results from *sharing* of electron pairs between two atoms The electrons shared belong to *both* atoms

Ionic Bonds

Results from attraction between large numbers of *cations* and *anions* Atoms *donate* or *accept* electrons from each other

Lewis Dot Diagram

Shows ONLY the valence electrons in an atom. The core electrons (inner electrons) still exist, but we don't see them in this model. Chemical symbol goes in the center and valence electrons go around it. Max of 8 valence electrons per diagram! Don't pair them up unless you have to!

Sublimation

Solids that sublime have very high vapor pressure. Ex: I2,CO2, naphthalene

Chemical Bonds

The attraction between the *nuclei* and *valence electrons* of different atoms that binds the atoms together

Kinetic Theory (In Terms of Temperature)

The idea that particles in matter are always in motion and that motion has consequences. As temperature rises, and pressure is held constant, KE increases and causes: solid, liquid, gas

Molecular Geometry/Shapes

The shape of a molecule plays an important role in its *reactivity*. By noting the number of *bonding* and *nonbonding* electron pairs we can easily predict the *shape* of the molecule.

Boiling Point

The temperature at which the vapor pressure of the liquid is equal to the atmospheric pressure. - Meaning, boiling point can change depending on the liquid and the atmospheric pressure.

Decanting

when liquid is poured off after the solid has settled to bottom ; can also be used to separate liquids if they form separate layers *Type of Mixture(s) Separated* - Heterogeneous only

Ionic Bonding

*1* All the electrons must be accounted for!

Physical Change

*A change in the form of the substance, but not the composition. No chemical bonds are broken (or formed)* - A change in one or more physical properties - Identity of the matter does not change - A change in state is a physical change Examples: Crumpling Bending Tearing Cutting Boiling Freezing Melting Crushing

Physical Properties

*A characteristic that can be observed or measured without changing the identity of the substance* Examples: Color Dissolving (solubility) Smell/taste/texture Luster - Shininess of a metal. Viscosity - Resistance to flow. Malleability - Hammered into sheets. Ductile - Drawn through a wire. Conducting heat and electricity Any changes of state Melting, freezing, boiling, condensing, subliming, depositing Density (mass/volume)

Molecule

*An uncharged group of two or more atoms held together by covalent bonds*

Octet Rule

*Atoms can become stable by having 8 (or 2 in the case of hydrogen) electrons in their outer energy level so they look like a noble gas*. An octet in the outer shell makes atoms stable. Electrons are lost, gained or shared to form an ion.

Boiling Vs. Vaporization

*Boiling* - Phase change of a liquid to a gas. Occurs ONLY at a specific temperature (the Boiling Point). Can occur at any place in the liquid. *Vaporiazation* - Phase change of a liquid to a gas. All phase changes of liquid to a gas either through evaporation or boiling.

Covalent

*Bonding Formation* - e- are shared between two nonmetals *Type of Structure* - True Molecules *Physical State* - Liquid or Gas *Melting Point* - Low *Electrical Conductivity* - No *Solubility in Water* - No *Other Properties* - Odorous

Ionic

*Bonding Formation* - e- are transferred from metal to nonmetal *Type of Structure* - Crystal Lattice *Physical State* - Solid *Melting Point* - High *Eletricial Conductivity* - Yes *Solubility in Water* - Yes

Chemical Change

*Changes the identity of the substance; forms new type of matter* The change of substances into other substances through the breaking of chemical bonds, rearranging of atoms, and formation of new chemical bonds A chemical change is referred as a chemical reaction. Examples: Oxidizing Rusting Tarnishing Digesting Browning Spoiling Combusting(burning) Evidence of chemical reaction: Formation of heat or light Gas bubbles means a gas is being created as a product Forming a precipitate solid is being created Color change Change in sound, smell, taste Change in heat - an increase or decrease of at least 5 degree celcius

Pure Substances

*Element* Located on the Periodic Table Represented by a symbol *Made out of the same atom (element)* Copper wire Aluminum foil Gold or silver bars *Compound* Represented by a formula Composed of identical molecules Composed of 2 or more elements in a fixed ratio Properties differ from those of individual elements Can only be broken down by a chemical reaction. Examples Table Salt (NaCl), Water (H20)

Law of Conservation Of Energy

*Energy cannot be created or destroyed* Energy is never gained or lost, it just changes form - Energy can take on many forms: heat, light, sound, kinetic (energy of motion), potential (energy of position, or stored energy)

The HONC Rule

*H*ydrogen (and *H*alogens) form *one* covalent bond *O*xygen (and sulfur) form *two* covalent bonds One double bond, or two single bonds *N*itrogen (and phosphorus) form *three* covalent bonds One triple bond, or three single bonds, or one double bond and a single bond Carbon (and silicon) form *four* covalent bonds. - Two double bonds, or four single bonds, or a triple and a single, or a double and two singles

2 types of mixtures

*Homogeneous* - Latin word "Homo", meaning "same". *Heterogeneous* - Latin word "Hetero", meaning "different".

Intensive Properties: Matter doesn't matter

*Independent* of the amount of substance present in a sample Examples: Color Magnetism Roughness Density Malleability

Superscript

*Indicates the charge of an ion*

Subscript

*Indicates the number of atoms or ions present in a chemical formula*

Formation Of Ionic Compound

*Lewis Dot Structures* can be used to demonstrate the *changes* that take place in *ionic* bonding Each element tries to achieve an *octet* of electrons Consider the atoms sodium and chlorine

Law of Conservation Of Matter

*Matter cannot be created or destroyed, only rearranged* - The same number and type of elements that go into a reaction also come out of a reaction in a different form

Prefixes

*Mono* = 1 *Bi* = 2 *Tri* = 3 *Tetra* = 4 *Penta* = 5 *Hexa* = 6 *Hepta* = 7 *Octa* = 8 *Nona* = 9 *Deca* = 10

How to draw them (NASL)

*Need*: Calculate the total number of *valence electrons* the atoms need to have their stable octet. *Available*: Count up the *total* number of valence electrons the atoms currently have. *Shared*: Subtract *NEED - AVAILABLE* and divide by *2* to get the number of bonds to the central atom. Lone: Subtract *AVAILABLE - SHARED* electrons to get your lone pairs. *Start* putting lone pairs on *central* atom until it has an octet, then fill in other octets

Types of Bonds

*Single* = 1 pairs of Electrons *Double* = 2 pairs of Electrons *Triple* = 3 pairs of Electrons

Going from 1 phase to another

*Sublimation* solid---Gas *Melting* Solid---Liquid *Evaporation* Liquid---Gas *Freezing* *Liquid---Solid* *Condensing* Gas---Liquid *Deposition* Gas---Solid

Types of Alloys

*Substitutional* - substitute some atoms for others. Remove atoms of one element and in their place, substitute atoms of another element *Interstitial* - small atoms fit in between the spaces left by larger atoms

Chemical Formula

*Used to represent the name of a chemical compound*

Paper Chromatography

*Used to separate mixtures based on mass. Different parts move quicker on paper than other. *Type of Mixture(s) Seperated* - Homogeneous liquids

VSEPR Theory

*Valence Shell Electron Pair Repulsion Theory* Electron pairs orient themselves in order to *minimize* repulsive forces.

Evaporation

- Liquid Gas but ONLY on the surface of the liquid! - Can occur at any temperature. - *Why do we evaporate? Some molecules move faster than others and are able to overcome the bonds between water molecules.* How to we make something evaporate faster? - Increase temperature - Increase surface area If we evaporate, what happens to the temperature of the liquid? - It goes down because we've removed the fastest moving particles. - The fastest moving particles have the most energy. The less energy there is, the lower the temperature.

Two Non-metals

-Always use prefixes, except when there is only one atom of the first element. -Change the ending of the second element only to ide.

Once you understand chemical names and formulas, you can figure out what chemical compounds are contained in different household products.

A) washing soda is *sodium carbonate* (Na2CO3) (B) oven cleaner is *sodium hydroxide* (NaOH), which is also known as lye.

Ion

An *atom* that has a positive or negative charge; electrons are lost, gained or shared to form an ion - Electrons are transferred from *metals* to *nonmetals* when forming ionic compounds - Metal becomes positively charged (cation) and the nonmetal becomes negatively charged (anion) - The attraction between the oppositely charged ions forms the ionic bond

Covalent Bond

Attraction of two atoms for a *shared* pair of electrons

Nonmetal Stem

C, S, Si, As—Drop last 2 letters in name: Carbon's stem is Carb- F, Cl, Br, I, Se—Drop last 3 letters in name: Fluorine's stem is Fluor- N, O, P—Drop last 4 letters in name: Nitrogen's stem is Nitr-

Homogeneous Mixtures

Can have more than one state of matter Uniform in composition NO VISIBLE PARTS (one phase) Also called a "solution" Examples: Vinegar Brass

Heterogeneous Mixtures

Can have more than one state of matter. Not uniform in composition Visible parts (2 or more phases) Examples: Chocolate chip cookies Fruit salad Blood Sand

Looking at an element Chemical Symbol

Chemical symbol is the one to two letter abbreviation. First letter is a capital, second letter is lower case. Some come from Latin words! Example: Tin (Sn) from the Latin word "Stannum"

Octet Rule

Compounds tend to form so that each atom, by *gaining or losing* electrons, has an octet of electrons in its highest occupied energy level. Helium and hydrogen are so small that they are stable with *2* valence electrons (only one energy level)

Lewis Dot Diagram for Nitrogen

Determine the number of valence electrons by looking at the group number in the US numbering system. Nitrogen has *5* Valence Electrons Then add *1* electron at a time to each side until they are forced to pair up.

Determining Molecular Shapes

Draw the Lewis Diagram. Count up e- pairs on *central *atom. double/triple bonds = ONE pair Shape is determined by the # of *bonding* pairs and *lone* pairs.

What determines the shape of a Molecule?

Electron pairs *repel* each other. Electron pairs try to get as far *apart* as possible from each other determining the shape of the molecule.

Electron Domains

Electron pairs on central atom are also *electron* domains. Double and triple bonds count as *one* electron domain.

Valence Electrons

Electrons in the highest (outermost) electron level Have most contact with other atoms Outer shells of noble gases contain 8 valence electrons (except He) Example: Ne 2-8 Ar 2-8-8

Learning Check

How are compounds and mixtures different? Compounds: fixed ratios, chemically separated. Mixtures: no fixed ratios, physically separated.

How do atoms get 8 valence electrons

If atoms collide with enough energy, their outer electrons will rearrange to achieve an octet of valence electrons. Atoms do this by: Transferring electrons (ionic compounds) Sharing electrons (covalent compounds)

Vapor to Gas

In any liquid or solid, some surface particles will "escape" into the gas phase. - Known as "vapor" Vapor particles exert pressure on the walls of the container. - Known as "vapor pressure" Increasing temperature leads to increase in vapor pressure, which eventually leads to boiling.

Compounds always have the *same* composition

Law of Definite Composition - A compound contains the same elements in exactly the same proportions by mass, regardless of how much you have or where you got it. What happens if you change a compounds fixed ratio? You have a NEW substance with its own properties! Example: H20, vs. H202

Exception to Octet Rule

Less than 8: Hydrogen: *2* in outer energy level Boron: *6* in outer energy level, and Be has *4* More than 8: anything in *3rd* period or heavier Because they may use the empty *d* orbital ex: S, P, I

Lewis Structure For Ionic Compounds

Lewis Structure For Ionic Compounds

Lewis Structure Covalent

Like dot diagrams but for entire *molecules* Atomic symbols represent *nucleus* and *core* electrons and *dots or dashes* represent *valence electrons* Unshared electrons: (lone pairs) pair of electrons not involved in bonding written around only *one symbol* Bonding electrons: written in between *2 atoms* as a dash Each atom tries to get an octet

Nonbonding Pairs & Bond Angle

Nonbonding pairs: Physically *larger* than bonding pairs. *Decrease* bond angles in a molecule.

Another way of indicating bonds

Often use a *line* to indicate a bond Called a *structural* formula Each line is *2* valence electrons

Physical Separation Techniques

Physical Separation Techniques

Physical Vs. Chemical Change

Physical Vs. Chemical Change

Naming Ternary Ionic Compounds

Polyatomic's name stays the same. If you have a positive polyatomic (i.e. ammonium) and a non-metal, change the ending of the non-metal to -ide. Ex: (NH4)2S Ans: Ammonium Sulfide

Molecular Compound

Represent each element with its symbol Add a subscript after each symbol to indicate the # of atoms of each element (if necessary). Remember, the *prefixes* in the name tell you how many of each type of atom are present in the compound

Filtration

Solid part is trapped by filter paper and the liquid part runs through the paper. *Type of Mixture(s) Separated* - Heterogeneous only

Distillation

Solid/liquid mixtures and liquid/liquid mixtures can be separated upon the boiling point of each liquid involved. The liquids are boiled off one at a time and move to a different area where they are condensed and collected. *Type of Mixture(s) Separated* - Both, but mainly for homogeneous mixtures of liquids

Melting/ Freezing Point

Temperature at which: - They are the same value! - Depends on whether you are gaining or losing KE. FYI: Some substances cannot be melted or boiled. These substances decompose if exposed to high temperatures. Ex: sugar

Magnets

Used to separate metals with magnetic properties. - Example: A magnet separates iron from sulfur. *Type of Mixture(s) Separated* - Heterogenous

Ionic Compounds

Write the symbol for each ion with its charge Determine how many of each ion are needed to make the total charge on the compound zero (or use the criss-cross method) Add a subscript after each ion's symbol to show the # of each ion in the compound Put polyatomic ions in ( ) when it is necessary to add a subscript. The new subscript goes on the outside of the ( ). *Do Not change subscripts in the formula of a polyatomic ion* Do not include the charges in your final answer

Vaporization

where the liquid portion is evaporated off to leave solid at room temperature *Type of Mixture(s) Separated* - Both hetero- & homogeneous