Chapter 2

Chapter 2

Chapter 2Elements are the Building Blocks of Matter1Pure Substance A material that is made up of particles that are identical to each other. (all the same)

Have their own set of properties - boiling point, density

Two types of Pure Substances - Elements (Gold, Hydrogen) - Compounds (Pure Water, Salt) Elements pure substance with 1 type of atom

cannot be broken down or separated into simpler substances.

109 different types of elements

Are arranged in a Periodic Table according to their Atomic Number (# of protons in their Nucleus)Elements and Chemical SymbolsIn chemistry each Element has its own symbol which is used to show chemical formulas. [ NaCl ]

Different ways to name Elements with symbols :First Letter - Carbon - CFirst (2) Letters - Cobalt Co First and Third - Chromium CrLatin or Non English - Iron Fe [ Ferrum ]

Use same symbols around the world to communicate with different countries. (common language)Twenty Common elementsSymbol is the first letter in nameSymbol is made from two letters in its nameSymbol is based on non-English nameHydrogen (H)Magnesium (Mg)Sodium (Na)Carbon (C)Calcium (Ca)Potassium (K)Nitrogen (N)Nickel (Ni)Iron (Fe)Oxygen (O)Zinc (Zn)Copper (Cu)Neon (Ne)Silver (Ag)Helium (He)Gold (Au)Chlorine (Cl)Mercury (Hg)Silicon (Si)Lead (Pb)5Symbols and Jokes

Element Jokes and Puns Question : Anyone know any jokes about sodium? Answer: Na

Please accept my apology !Sorry for making bad chemistry jokes but all the good ones Argon !!!!!!

Lets Get Serious one more

Question to considerWhat is the difference between Co and CO?

(hint look at the periodic table for help)

10 Atomic Number and Mass NumberEach Element has (2) numbers written in the periodic table.

Atomic Number - smaller number that tells you the number of Protons and Electrons in an atom

Mass Number -bigger number that tells you how heavy the atom is (amu)Mass # = proton # + neutron #

Copy into notebook (example) # Protons (Electrons)

# Protons + Neutrons

Element - Atomic # and Mass #

Element Atomic # and Mass#

Examples

New Element Discovered !!!!

Time for one more PUN ..Silver walks up to Gold in a party and says, "Au, get outta here!

We would like to apologize for not adding more element jokes... but we only update them.... Periodically !!!

The First Periodic Table First designed by Dmitri Mendeleev (1869)

First table consisted of only 63 elements.

He left spaces for future elements that would be later discovered

The table was later finished by later scientists.Mendeleevs Periodic Table

There are a lot of gaps, but look at the horizontal rows (periods) and compare to the current periodic table.20Current Periodic Table

21Periodic Table (General Characteristics) Periodic table: a chart that organizes all known elements according to their physical and chemical properties

Arranged according to Atomic Number(Number of protons ) increases from (Left ---Right) Made up of (2) Major Groups: Metals and Non-Metals

Has (7) Rows - (Periods)Has (18) Columns (Groups) or (Families)

Periodic TableTable is made up (2) major groups (Metal and Non metals) separated by a Ladder Shaped Line

Periodic Table Remember that there are (3) Groups of elements in the Periodic Table : 1) Metals , 2) Non- Metals and 3) Metalloids or Semi Metals.

Elements are grouped on the basis of similar characteristics(3) major groups of Elements are: Metals, non-metals and Metalloids (semi- metals)

Ductile: ability of a substance to be pulled or stretched.

Malleable: ability of a substance to be bent or molded into different shapes.

MetalsNon-metalsMetalloids ShinyDuctileMalleableConducts heatConducts ElectricityDullNon-ductileNon-malleableDoes not conduct heatDoes not conduct electricityShiny or dullNot ductileNot malleablePoor heat conductorMay conduct electricity25Color our Periodic Table Metals Blue Non- Metal RedMetalloids (Semi-Metals)- circle them

Some other Special Groups within the Periodic TableTransition Metals - (tough metals) - center of Periodic Table

(4) Special Groups or Families (columns)Alkali Metals (Group 1) ( 1) Alkaline Earth Metals (Group 2) . (2)Halogens (Group 17) . or (Vii)Noble Gases (Group 18). (Viii) or (0)

Special Groups of Elements

Alkali Metals Family 1 (Group 1)Alkali Metals (Column 1)Very reactive and softReact with water, oxygen and other non-metalsLow melting points Reactivity increases as you move down the column

29Alkaline Earth Metals Family 2 (Group 2) Alkaline Earth Metals (column 2)Less reactive than Alkali MetalsBurn in air if heated, produce bright flames and used in fireworksAlso reacts with waterReactivity increases as you move down the column

30Halogens- Family 17 (Group 17) (Group vii) Halogens (Column 17)Non-metals and highly reactiveFluorine and Chlorine are gases, Bromine is a liquid and Iodine is a solidReactivity decreases as you move down the columnAstatine is very rare and little is known about it

31Noble Gases- Family 18 (Group 18) (Group Viii or 0) Noble gases (column 18)Most stable and unreactive elements

At room temperature they are colorless and odorless

Some gases, like Argon and Neon are used in light fixtures

Helium is lighter than air and is used in balloons.32Noble Gas Joke Helium walks into a restaurant , The waitress says "We don't serve noble gasses in here."

Helium doesn't react.Another Chemistry JokeTwo chemists go into a restaurant. The first one says "I think I'll have an H2O."

The second one says "I think I'll have an H2O too"

and he died.Locating Elements on the Periodic TableMake sure you can identify the relative position of elements on the periodic table

What element is located at period 2, family 3?Boron35Bohr Rutherford DiagramsNeed to review the AtomProtonsElectrons NeutronsEnergy Levels 2,8,8,18

Atomic StructureBohr-Rutherford Diagram: shows how many electrons are in each energy level (electron shell) surrounding the nucleus.

Energy Level (or electron shell): the space around the nucleus in which the electrons may be found.Known as the 2-8-8-18 pattern

The shell closest to center can hold 2 electronsThe 2nd shell can hold up to 8 electronsThe 3rd shell can hold up to 8 electronsThe 4th shell can hold up to 18 electrons.37How to Draw Bohr-Rutherford ModelsStep 1: Draw NucleusStep 2: Put symbol, number of protons and number of neutrons in the NucleusStep 3: Use the 2-8-8-18 pattern to fill the energy levels.

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Bohr Rutherford Diagram Example Diagram that includes (2) parts inside the nucleus (number of protons and neutrons)energy levels around the nucleus (electrons)

Example (Sodium) Bohr- Rutherford Diagram

and electrons

How to Draw Bohr-Rutherford ModelsStep 1: Draw NucleusStep 2: Put symbol, number of protons and number of neutrons in the NucleusStep 3: Use the 2-8-8-18 pattern to fill the energy levels. NOTE: the first energy level is filled first completely before going to the second, the second is filled before going to the third and so on.

Draw Bohr Rutherford Diagram for MagnesiumSee page 62, figure 2.24

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41Bohr-RutherfordValence Energy Level: the energy level that is the furthest from the nucleus

Valence Electrons: Electrons that are furthest away from the nucleus.They occupy the valence energy level

42Patterns Observed Using Energy Level DiagramsElements in the same family have the same number of electrons in their valence energy level

Period number indicates the number of energy levels

The valence energy level structure determines how one element will react with another. Group 1 and Group 17 (Vii)

If the valence level is full, then it is difficult to react (look at Noble gases)

Website to show the similar properties of elements in familieshttp://videos.howstuffworks.com/hsw/5793-periodic-table-families-video.htm43