Bonding 3.1.3 Flashcards
What are three types of strong chemical bonds
Ionic, covalent and metallic
Explain ionic bonding
How are positive ions are negative ions attracted to eachother
What is the structure of an ionic compound and explain it
-Electrons are transferred from a metal to a non metal
Metal ions lose electrons to form positive ions, and non metal ions gain electrons to form negative ions
-Positive ions and negative ions are attracted together by strong electrostatic forces
-Giant ionic lattice where the same basic unit is repeated and it is Cube shaped
What are the properties of ionic Compounds and explain them
HIGH MELTING POINT: Strong electrostatic forces betweeb positive ions and negative ions, this requires a lot of energy to overcome
CONDUCTS ELECTRICITY WHEN MOLTEN OR IN SOLUTION BUT NOW WHEN SOLID: Ions are free to move through the structure and carry charge, in a solid, they are fixed by strong ionic bonds so cannot move
USUALLY SOLUBLE IN WATER: Water molecules can pull ions away from the lattic causing it to dissolve
BRITTLE AND SHATTERS EASILY: Forms a lattice od alternating positive ions and negative ions, when it is hit, it causes the ions to move and causes contact between ions with the same charge so they repel eachother
When is ionic bonding stronger and the melting point higher
When the ions are smaller and have higher charges
What is the attraction between in metallic bonding
Positive metal ions and delocalised electrons
What charge does a magnesium ion have
2+
What 3 things does the strength of metallic bond depend on
-The more protons, the stronger the bond
-Number of delocalised electrons per ion, the more delocalised electrons, the stronger the bond
-Smaller the ion, stronger the bond
What are the 3 properties of metal and explain them
High melting point: Strong electrostatic forces of attraction between the positive metal ions and delocalised electrons
Good conductors of electricity: Delocalised electrons can move and carry a current
Metals are malleable and ductile: There are no bonds holding the specific ions together, he layers of metal ions can slide over wachother so metals can be shaped
What are the 3 properties of metal and explain them
High melting point: Strong electrostatic forces of attraction between the positive metal ions and delocalised electrons
Good conductors of electricity: Delocalised electrons can move and carry charge
Metals are malleable and ductile: There are no bonds holding the specific ions together, he layers of metal ions can slide over wachother so metals can be shaped
Explain covalent bonding
What holds together the atoms
Shared pair of electrons between non metal atoms
Strong electrostatic forces of attraction between the nucleus and shared electrons
Explain the properties of simple covalent molecules
Low boiling point: Weak van der waal forces between moelcules that are easily broken
Do not conduct electricity: Molecules are neutral, no delocalised electrons or ions to carry charge
What is special about coordinate bonding
One atom provides both the electrons
How does a coordinate bond form
The atom that is giving the electrons has a lone pair of electrons
The atom that accepts the electrons is an atom that does not have a filled outer shell(atom is electron deficient)
What bonding is this?
NH3 + H+ -> NH4+
Coordinate bonding
In a displayed formula for coordinate bonding, what way does the arrow face
It faces to where it is giving electrons
Bonding Samsung notes
Yayayay
What are the two types of electron pairs molecules and ions have
Bonding pairs and lone pairs
Pairs of electrons exist in a charge cloud. What is a charge cloud?
The area where the electron pair is most likely to be found
What is electron pair repulsion
Electron pairs will repel eachother as far as possible
State the different combinations of electron pairs in order from lowest repulsion to highest repulsion
Bonding pair/Bonding pair
Bonding pair/Lone pair
Lone pair/Lone pair
What is the shape of any molecule/ion determined by and how?
The number of electrons pairs which repel eachother as far as possible
For molecules which have no lone pairs, state the NAME of the molecule and its BOND ANGLE from 2 to 6 electron pairs
2 pairs - linear - 180°
3 pairs - trigonal planar - 120°
4 pairs - tetrahedral - 109.5°
5 pairs - trigonal bipyramidal- 120°,90°
6 pairs - octahedral - 90°
Shapes Samsung notes
Hi
What are the steps to working out the shape of molecules/ions
1) What is the central atom
2) How many electrons are in its outer shell
3) How may electrons from the other bonded atoms
4) Add up the electrons (positive ions- subtract an electron/negative ions-add an electron) and divide by 2 to find the number of electrons pairs
5) How many are bonding pairs, the rest are line pairs
For each lone pair, what does the bond angle decrease by(Tetrahedral)
2.5°
Draw the shape of molecules with 2 electron pair and state the bond angles
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Draw the shape of moelcules with 3 electron pairs and state the bond angles
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Draw the shape of molecules with 4 electron pairs and state the bond angles
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Draw the shape of moelcules with 5 electron pairs and state the bond angles
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Draw the shapes of moelcules with 6 electron pairs and state the bond angles
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In covalent bonds, the electrons shared by the atoms will not be evenly distributed if..
E.g. in H - H, the electrons are …
In H - Cl, the electrons are …
One atom is better at attracting electrons than the other atom
in H - H, the electrons are shared equally
In H - Cl, the electrons are pulled more towards the Cl
Define electronegativity
The power of an atom to attract the pair of electrons in a covalent bond towards itself
What factors affect electronegativity
Nuclear charge
Atomic radius
Sheilding
What is electronegativity measured on
Which few elements have the largest electronegativity(highest to lowest)
Where are these elements located on the periodic table
The pauling scale
F O N Cl (phone call)
Top right corner
What is the trend of electronegativity as you across the period
Electronegativity increases as nuclear charge increases, atomic radius decreases, same sheilding so more attraction for bonding electrons
What is the trend of electronegativity as you go down a period
Electronegativity decreases as sheilding increases, atomic radius increased, bonding electrons ate further from the nucleus so less attraction for the bonding electrons
A polar covalent bond forms when elements in the bond have…
When a bond is a polar covalent bond, it has an uneven distribution of electrons in the bond and produces a…
The element eith the larger electronegativity in a polar compound will be the …
A polar covalent bond forms when elements in the bond have different electronegativities
When a bond is a polar covalent bond, it has an uneven distribution of electrons in the bond and produces a charge seperation(dipole) delta+ and delta- ends
The element with the larger electronegativity in a polar compound will be the delta- end
Polar molecules are due to the effect of…
Polar molecules are due to the effect of the polarity of all the bonds in a molecule
If the polar bonds are arranged symmetrically…
If the polar bonds are arranged symmetrically, the dipoles cancel eachother out so the moelcule has no permanent dipole and is non polar
If the polar bonds are arranged so that they all point roughly in the same direction…
If the polar bonds are arranged so that they all point roughly in the same direction, the dipoles don’t cancel eachother out so the charge across the whole molecule will be uneven -> molecule will have a permanent dipole and is polar
Is C or H more electronegative
They have similar electronegativity so do not form dipoles when bonded to eachother
Polar molecules SAMSUNG NOTES
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Exam practice
Explain how the electron pair repulsion theory can be used to deduce the shape of and the bond angle of…
The central atom is.. and it has… outer electrons. …. electrons come from the other bonded molecule. … electrons in total so there are …. electrons pairs.
-State number of bonding pairs and lone pairs
-Electron pairs repel to be as far away from eachother as possible
-If there are no lone pairs, electron pairs repel equally
-If there are lone pairs of electrons, state that lone pairs repel more than bonding pairs
-State shape and bond angle
If the intermolecular forces are strong enough, then moelcules are held closely enough together to be…
Liquids or even solids
What are 3 types of intermolecular forces
Dipole-dipole forces
Van der Waals forces (temporary dipole)
Hydrogen bonding
In Dipole-dipole forces, difference in electronegativity leads to….
Dipoles don’t…….. so the molecules has an overall ……
How are the dipoles held together?
In Dipole-dipole forces, difference in electronegativity leads to bond polarity
Dipoles don’t cancel out so the molecules has an overall permanent dipole
The delta+ part of a moelcule is attracted to the delta- part lf another molecule as opposite charges attract
Define intermolecular forces
Define intramolecular forces
Intermolecular forces: Weak electrostatic forces holding molecules together
Intramolecular forces: Strong covalent bonds joining atoms within the molecule
Where do Van der Waals forces occur
They occur between all molecules and atoms
Explain how Van der Waals forces are formed
-Electrons in charge clouds are constantly moving very fast
-Random movement of electrons in one moelcule creates a temporary dipole
-This induces a dipole in a neighbouring molecule
-The temporary attraction between the delta+ end of one moelcule and delta- end of the neighbouring molecule in called Van der Waals forces
What affects Van der Waals forces and explain it
-The more electrons there are in a molecule, the more likely temporary dipoles will form, Van der Waals forces will also be stronger so boiling point will be higher
-Shape of molecule,long chain alkanes have a larger surface area of contact between molecules for Van der Waals forces to form compared to spherical shaped or branched alkanes, stronger Van der Waals forces
When does Hydrogen bonding occur in a compound?
It occurs in Compounds that gave a Hydrogen atom attached to one of the 3 most electronegative atoms (F,O,N) which must have an available lone pair of electrons
When drawing Hydrogen bonding, what are the 3 features you must include
Must show dipoles
Must show all lone pairs
The H attached to 2 other atoms (F/O/N) has to be linear
Hydrogen Samsung notes
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State the weakest to strongest forces found in Covalent molecules
Van der Waals
Dipole Dipole
Hydrogen bonds
Explain Hydrogen bonding In liquid water and ice
In liquid water, hydrogen bonds constantly break and reform becuase moelcules are moving
In ice, hydrogen bonds hold the molecules in fixed positions, molecules are further apart in ice than water so density is lower
What is the arrangement of particles in solid, liquid and gas
What is the spacing of particles in solid, liquid and gas
What is the movement of particles in solid, liquid and gas
Regular, irregular, irregular
Close, close, far apart
Vibrate in fixed positions, rapid movement, very rapid random movements in all directions
Freezing Samsung notes
❄️☃️
Describe the structure of graphite
Consists of layers of carbon atoms
Each carbon atom joined to 3 other carbon atoms
The carbon atoms within each layer is joined by strong covalent bonds
There are weak van der waals forces between the layers
Explain the properties of graphite
HIGH MP AND BP: It has a macromolecular structure, carbon atoms are held by strong covalent bonds which requires lots of energy to break
CONDUCTS ELECTRICITY: Delocalised electrons can move through the structure and carry charge
SOFT/FLAKY/LUBRICANT: Carbon atoms are arranged in layers, weak van der waals forces between layers so the layers can slide over eachothed
Explain the structure of diamond
Tetrahedral structure
Each carbon atom is bonded to 4 other carbon atoms
Explain the properties of diamond
HIGH MP AND DP: It has a macromolecular structure, carbon atoms are held together by strong covalent bonds which requires lots of energy to break
CONDUCTS ELECTRICITY: No delocalised electrons so can’t carry charge
HARD AND STRONG: Rigid structure rather than a layered structure
EXAM QUESTION
The sturtcure and boiling points of —- and —– are shown
Explain, in terms of structure and bonding, why the boiling point of —— Is higher than the boiling point of —–
EHAT IS THE FORNST FOR THE ANSWER
-The highest boiling point has —- bonding (give the strongest one)
-The lowest boiling point has —-
- —- bonding is stronger than —–
