Bonding Flashcards
How do you determine if a bond is ionic?
The difference between each atom’s electronegativities are 1.7 or greater
OR
There are metals and non metals in the compound
What is a bond?
When two nuclei simultaneously attract the same pair of electrons
What are the 3 types of bonds?
Ionic, Covalent, and Metallic
How are electrons distributed in an IONIC bond?
Transfer of electrons from the metal to the non metal
What happens to the metal and non metal in an ionic bond?
The metal becomes a positive cation and the non metal becomes a negative anion
How are electrons distributed in a COVALENT bond?
The electrons are shared between the non metals
How can you tell if a bond is covalent?
The difference in EN is <1.7
OR
There are two non metals in the compound
How can you tell if a bond is metallic?
There are two METALS in the compound
What is a NON POLAR covalent bond?
- The equal sharing of electrons
- Occurs between two of the same non metal
- No difference in EN
- Symmetrical electron distribution
What are partial charges?
Partial charges occur when there is uneven sharing of electrons. The atom with greater electronegativity (EN) attracts the electrons more, making it partially negative while the other side is positive because it is losing it’s electrons.
Do partial charges happen in non polar covalent bonds?
No, because both atoms have the same EN, so neither atom pulls each other’s electrons.
Do partial charges happen in POLAR covalent bonds?
Yes, because the atoms are of different type, making one atom stronger than the other.
What is a POLAR covalent bond?
- Uneven sharing of electrons
- Non metals of diff types
- Diff in EN is between 0.4 and 1.7
- Asymmetrical charge distribution
What is a metallic bond?
- Occurs between two metals
- Electrons float in a sea of mobile electrons
What makes a metals good conductors?
Its mobile electrons
Why do atoms pair and lose or gain electrons to do so?
To get a full octet (8) valence electrons to make them stable
What process is breaking bonds?
Endothermic, because it requires energy to break
What process is forming bonds?
Exothermic, because it releases excess energy when the bond is formed
What is a weak bond?
- Takes little energy to break
- Takes little energy to form
What is a strong bond?
- Takes lots of energy to break
- Takes lots of energy to form
For the following equation:
N(g) + N(g) → N2(g) + Energy
is a bond being formed, or broken and is energy being absorbed or released?
Formed, Released
What is a non polar MOLECULE
when a compounds electron distribution is symmetrical
OCCURS in non polar or polar bonds
What is a polar MOLECULE
When a compounds electron distribution is asymmetrical
What is a the difference between a polar bond and molecule
A polar bond is when two non metals (different) unevenly share electrons. A polar molecule is when atoms shape is asymmetrical.
What are the molecular shapes?
Tetrahedral, Linear, Bent, Trigonal Pyramidal, Trigonal Planar
What are inter molecular forces?
Forces BETWEEN molecules holding them together.
The strength of IMF increases with:
Polarity, Mass, Electron #
IMF influences
Boiling Pt, Melting Pt, Phase
What is hydrogen bonding found between?
Found between atoms containing Hydrogen and Fluorine, oxygen or nitrogen.
Hydrogen bonding is…
- Not an actual bond, just a force between atoms
- Strongest IMF
Examples of hydrogen bonding
H2O, NH3
What does hydrogen bonding do?
Strong hydrogen bonding gives water it’s cohesive properties and high boiling points.
The exception to the EN 1.7 rule:
Any group 1 or group 2 metal bonded to hydrogen is ionic
Polyatomic Ions
Some ionic compounds that have more than 2 elements contain polyatomic ions (TABLE E)
How to draw molecular (covalent) lewis dot diagrams
1: Add an 8 for each element each compound but 2 for H
2: Add up all valence electrons for a second #
3: subtract valence # from octet number
4: Divide by two (that’s # of bonds)
5: Draw and label extra with dots
Tip for molecular (covalent) lewis dot diagrams
Hydrogen only forms one bond!
S
N
A
P
S = symmetrical N = nonpolar A = asymmetrical P = polar
High IMF
Phase: Solid
Low IMF
Phase: Gas
Vapor Pressure with IMF
High IMF : Low VP
Low IMF : High VP
Ionic Bonding Facts
- High Melting Pt
- Hard
- Conducts electricity as a liquid and aq
Why do things conduct electricity in water?
They have mobile ions
Covalent Bonding Facts
- Low Melting Pt
- Soft
- BAD conductivity
Metallic Bonding Facts
- High Melting Pt
- Hard
- Conduct electricity as a solid and liquid
What two elements are liquids?
(BrHg)
Bromine and Mercury
Do ionic compounds have a shape?
NO!
Anything with hydrogen bonding has:
High boiling pts and cohesive properties
Combustion
- Buring something and exothermic
- Water and CO2 produced
Synthesis
2 or more substances combine to form one larger one
ex: A + B ——-> AB
Decomposition
A compound is broken down into two or more substances
ex: AB ——> A + B
Synthesis and Decomposition are
OPPOSITE!
Single Replacement
Reactants have an element and compound and if the element is more reactive, it will replace one in the compound
ex: AB + C ——> A + BC
Double Replacement
2 compounds combine and 2 new ones are formed
ex: AB + CD ——-> AC + BD
How do you use table J to figure out if single replacement will happen?
More active (higher up in scale) will replace less reactive metal in compound
What do we use Table F for?
To see if a compound is soluble or insolube
