Transcript Chemical reactions Part 2

Take a half sheet of paper and answer
the following….
1. What is located inside the nucleus of an
atom? (protons, neutrons, or electrons)
2. What is found on the outside?
3. What is the atomic number equal to?
4. How do you calculate the number of
neutrons there are in an atom?
Periodic table
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AYDEN IS HERE!
Chemical Reactions Packet 2
Lewis Dot Structures
• Illustrates the number of valence electrons
– Valence electrons = Number of electrons in outer
shell
– Placed around the symbol of the element
• Helps us determine how compounds are
formed / how elements bond
– The group # gives you the number of valence
electrons
Valence electrons on the periodic table
Lewis Dot Structures
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Steps to create Lewis Dot Structures
● Drawing Valence Electrons
○ How many valence electrons does Fluorine have?
7
○ Start at 12:00 with your first dot
○ Add dots at 3:00, 6:00, and 9:00 moving clockwise until you reach the correct number of
dots
○ You need one dot at each location before you start adding your second dots
Practice
• Lewis Dot Diagram Practice
● Draw the Lewis Dot Diagram for Phosphorus
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Phosphorus
Symbol: ____
Atomic Number: _____
Atomic Mass: ____
Protons: ____
Neutrons: _____
Electrons: _____
Valence Electrons: _______
Practice Answers
• Lewis Dot Diagram Practice
● Draw the Lewis Dot Diagram for Phosphorus
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Phosphorus
Symbol: __P__
Atomic Number: __15___
Atomic Mass: _31___
Protons: __15__
Neutrons: __16___
Electrons: __15___
Valence Electrons: ___5____
Ionic Bonding
• Elements Goal = Stability
– Elements want to be stable
– In order to be stable they need to fill their
outermost energy level completely
• “Complete its octet” (oct meaning 8)
• When outer level is filled
– No Charge = Stable
• When outer level is not filled
– Charge = Unstable
How do we figure out and elements
charge?
– Charge is determined by how many electrons they
need to gain or lose to complete their outer level
– Every element in the group has the same charge
• Example: All Halogens are -1
Practice
Group
1
2
13
14
15
16
17
18
Charge
+1
+2
+3
+/- 4
-3
-2
-1
0
Types of bonds
Ionic Bonds
Covalent Bonds
Forms between a metal and a
nonmetal.
Forms between a nonmetal and a
nonmetal
Electrons are transferred
Electrons are shared
Strong Bonds
Weak bonds
Hard / Brittle
Relatively Soft
Soluble in Water
Insoluble in water
High melting and boiling points
Low melting and boiling points
Conducts electricity
Does not conduct electricity
Solid at room temperature
Liquids and gases at room
temperature
Ionic bonds
• Ionic Bonds
– Bond in which one or more electrons from one
atom are removed and attached to another atom.
– It is when atoms transfer electrons
• One element gives electron
• One element takes electron
How does ionic bonding work?
–Ionic Bonds occur between metals and
nonmetals.
–Opposite charges are going to attract
–Their charges will cancel out and
become 0
• 0 = Stable
• Example:
• +1 + -1 = 0
• +2 + -1 Does NOT equal 0 so you would
need another -1 atom (of the same element)
How does the sharing work?
– Na has the 1 lone electron to share in its
outermost level
– Cl needs 1 to complete its octet
– Na will give 1 electron to Cl
Ionic Bonding Steps
Step 1: Write charges to determine the
number of atoms that are needed
Step 2: Write Lewis dot diagrams with
arrow showing electron movement
Step 3: Write Final Compound
Ionic Bonding Problem: Sodium and
Sulfur
Step 1: Write charges to determine the number of atoms that are needed
1 + 1 -2=0
Step 2: Write Lewis dot diagrams with arrow showing electron movement
Step 3: Write Final Compound
Naming Ionic Compounds (ADV. only)
• There are 3 ways to name ionic compounds
• We will focus on one way for a normal metalnonmetal ionic compound.
– Step 1- write down the name of the name of the
name of the metal element.
– Step 2- write down the name of the nonmetal
– Step 3- remove the “-ine” at the end of the nonmetal and replace with “-ide”
Bonding of atoms
• Why do atoms bond?
– Each atom wants a full outermost energy level
• How do they do this?
– By gaining/losing (ionic bond), or sharing (covalent
bond) valence electrons to achieve the duet or
octet rule aka: “being happy or stable”
– Gives each atom an electron configuration similar
to that of a noble gas
• Ex. Group 18: He, Ne, A
Types of bonds
Ionic Bonds
Covalent Bonds
Forms between a metal and a
nonmetal.
Forms between a nonmetal and a
nonmetal
Electrons are transferred
Electrons are shared
Strong Bonds
Weak bonds
Hard / Brittle
Relatively Soft
Soluble in Water
Insoluble in water
High melting and boiling points
Low melting and boiling points
Conducts electricity
Does not conduct electricity
Solid at room temperature
Liquids and gases at room
temperature
Covalent Bonds
• Definition
• A chemical bond in which two atoms share a pair
of valence electrons
• Always formed between nonmetal and nonmetal.
• How to Draw Covalent Bonds
• Step 1: Draw the Lewis Dot structures and circle
the electrons that are being shared
• Step 2: Redraw the bond using a line (it replaces
the circle)
• Step 3: Write the final compound
Covalent Practice: Chlorine and
Chlorine
Step 1: Draw the Lewis Dot structures and circle the
electrons that are being shared
Step 2: Rewrite the elements with a line
representing each shared pair (it replaces the circle)
Step 3: Write the final compound
What is the difference between a molecule and a
compound?
– Molecule - When two or more atoms are joined
together chemically
• Examples
– Carbon Dioxide - CO2
– Ozone - O3
– Water - H2O
– Compound - When two or more elements are joined
together chemically
• Examples
– Carbon Dioxide - CO2
– Ozone cannot be an example because there aren’t two different
elements
– Water - H2O
– All compound are molecules but not all molecules are
compounds
Simple Molecule
Complex Molecule
Hundreds or thousands of atoms bonded together,
in a repeating pattern to form a polymer
Only a few atoms bonded together
Possible because carbon atoms form very stable
bonds with other carbon atoms
Examples:
● Water molecules (H20)
● Ammonia (NH3)
● Methanol (CH4O).
Examples:
● Crystals
○ Diamonds
○ Graphite (pencil leads)
Counting simple and complex
molecules
You write each element (elements only have one
capital letter) and count how many of them there
are
C- 1
O- 1
H-4
C- 6
O-6
H - 12
Organic vs Inorganic Molecules (ADV
only)
Organic Molecule
Inorganic Molecule
Contain carbon and hydrogen bonds
Can contain carbon OR hydrogen but
NOT both
Associated with living things
Associated with non-living things
Examples include nucleic acids, fats,
sugars, proteins, enzymes and
hydrocarbon fuels.
● Table sugar or sucrose, C12H22O11
● Methane, CH4
Examples include salts, metals, and
substances made from single
elements
● Table salt or sodium chloride,
NaCl
● Carbon Dioxide, CO2
● Diamond (pure carbon)
● Silver