Bonding Flashcards
Ionic Bonding forms between…
A metal and non-metal.
Ionic Bonding is…
The electrostatic forces of attraction between the oppositely charged ions.
In Ionic Bonding, electrons are…
Transferred.
In Ionic Bonding, metals…
Lose electrons to form positive ions (cations).
In Ionic Bonding, non-metals…
Gain electrons to form negative ions (anions).
Opposite ions..
Attract.
Like ions…
Repel.
Why do Ionic compounds have high boiling and melting points?
Ionic compounds have strong electrostatic forces of attraction between the oppositely charged ions which requires a lot of energy to break the bonds.
Why don’t Ionic compounds conduct electricity when solid?
Ions are held together strongly and therefore can’t move.
Why can Ionic compounds conduct electricity when molten or dissolved in water?
The ions are free to move and carry the current = delocalised electrons.
Why are Ionic compounds described as being hard and brittle?
Ions cannot move or slip over each other easily.
Are Ionic compounds soluble or insoluble in water?
Soluble.
If a non-metal gains two electrons, what charge will it have?
2-
If a metal loses one electron, what charge will it have?
1+
What is Covalent Bond?
A shared pair of electrons.
A Covalent Bond forms between…
Two non-metals.
In Covalent Bonding, atoms…
Share electrons.
Why do atoms share electrons in Covalent Bonding?
To get to the nearest noble gas electronic configuration.
Fluorine reacts with Bromine to form liquid Bromine Trifluoride (BrF3). State the type of bond between Br and F in BrF3 and state how this bond is formed.
Type of bond: Covalent.
How bond is formed: Shared pair of electrons.
Name the type of bonding in Sodium Chloride.
Ionic Bonding.
Suggest the type of crystal shown by OF2.
Simple Molecular (Simple Covalent)
Are Simple Covalent Compounds/Molecular Crystals usually solid, liquid or gases?
They are usually gases or volatile liquids.
What are the three types of Intermolecular Forces?
Van der Waals
Permanent dipole-dipole
Hydrogen Bonding
What is meant by the term Electronegativity?
The ability of an atom to withdraw (attract) electrons from a covalent bond to itself.
Most electronegative element?
Fluorine.
What are the four most electronegative atoms?
Fluorine, Oxygen, Nitrogen and Chlorine.
Why does electronegativity INCREASE across a period?
The nuclear charge increases, shielding stays the same and electrons become more strongly attracted to the atom.
Why does electronegativity DECREASE down a group?
The distance between the nucleus and the outer electrons increases, shielding increases and electrons become less attracted to the atom.
Why can’t Noble Gases be described as electronegative?
They do not form bonds.
What is the strongest Intermolecular Force?
Hydrogen Bonding.
Van der Waals forces become stronger as…
The number of electrons increase and when there is a greater surface area.
Hydrogen bonds will form if…
- A molecule contains a Hydrogen atom covalently bonded to a Nitrogen, Oxygen or Fluorine atom.
- There is a lone pair of electrons on the N, O or F atom.
Hydrogen Bonding is represented by…
A dashed line that ends at a lone pair of electrons on the electronegative element N, O or F.
Lone pair / Lone pair bond angles are..
The biggest.
Bonding pair / Bonding pair bond angles are…
The smallest.
Lone pair / Bonding pair bond angles are…
The second biggest.
What is a lone pair of electrons?
Unshared electrons.
3 bonded pairs. No lone pairs. Angle: 120.
Trigonal Planar.
Octahedral?
6 bonding pairs. No lone pairs. Angle: 90.
5 bonded pairs. No lone pairs. Angle: 90 and 120.
Trigonal Bipyramidal.
Square Planar?
4 bonded pairs. 2 lone pairs. Angle: 90.
T-Shaped?
3 bonded pairs. 2 lone pairs. Angle: 90.
3 bonded pairs. 1 lone pair. Angle: 107.
Trigonal Pyramidal.
Linear?
2 bonded pairs. No lone pairs. Angle: 180.
2 bonded pairs. 2 lone pairs. Angle: 104.5.
Bent Planar.
Tetrahedral?
4 bonded pairs. No lone pairs. Angle: 109.5.
Shape of PCl3?
Trigonal Pyramidal.
Shape of CO2?
Linear.
Shape of NH4+?
Tetrahedral.
Shape of CO3(2-)?
Trigonal Planar.
The four types of Crystals are…
1 - Ionic
2 - Metallic
3 - Molecular (Simple Covalent)
4 - Macromolecular (Giant Covalent)
Two main examples of Macromolecular Crystals…
- Diamond
* Graphite
A Co-Ordinate / Dative Bond forms when…
The shared pair of electrons in the covalent bond are donated from one atom.
For a co-ordinate / dative bond to form…
- One atom must have a lone pair of electrons.
* The other atom must have a vacant orbital (empty orbital).
A dative covalent bond is represented by…
A short arrow from the atom/donor providing both electrons to the atom/acceptor of the electron pair.
NHF2 + BF3 > F2HNBF3
State the type of bond formed between the an atom and the B atom in F2HNBF3. Explain how this bond is formed.
Type of Bond: Dative/Co-Ordinate Bonding.
How the bond is formed: The lone pair of electrons on the Nitrogen are donated to Boron (empty orbital).
A Metallic Bond is…
The electrostatic force of attraction between the positive metal ions and the delocalised electrons.
3 main factors that effect the strength of a metallic bond are…
1 - The number of outer delocalised electrons.
2 - Size of the ion. (Smaller the ion, stronger the bond)
3 - Number of protons / nuclear charge.
Describe the structure of a Magnesium Crystal.
A lattice of positive ions surrounded by a sea of delocalised electrons.
Explain why metals are usually malleable and ductile.
Ions can slide over one another and the delocalised electrons prevent repulsion between the positive ions.
How does a metal conduct electricity?
When solid and molten. Electrons are delocalised therefore they can move through the structure and carry the charge.
Are Metallic Bonds soluble or insoluble in water?
Insoluble.
An Aluminium Chloride molecule reacts with a Chloride ion to form the AlCl4(-) ion. Name the type of bond formed in this reaction. Explain how this type of bond is formed in the AlCl4(-) ion.
Type of Bond: Dative.
Explanation: The lone pair of electrons on the Cl- are donated to the empty orbital in AlCl3.
State the type of Crystal structure for each of Iodine and Graphite.
Iodine - Simple Molecular.
Graphite - Macromolecular.
Carbon in Graphite is covalently bonded to…
3 other Carbon atoms.
Describe the structure of and bonding in Graphite and explain why the melting point of Graphite is very high.
Graphite is arranged in layers of Carbon atoms (hexagons). Each Carbon is covalently bonded to 3 other Carbon atoms. Graphite has a very high melting point because of the strong covalent bonds in the macromolecular structure. It requires a lot of energy to break the strong covalent bonds. There are also weak Van der Waals forces between the layers in Graphite.
Explain why Iodine vaporises when heated gently.
The weak Van der Waals require little energy to break the forces between the molecules.
State why Iodine is a very poor conductor of electricity.
The electrons are not delocalised therefore they are not free to move/carry the charge.
Suggest a value for the bond angle in the H3O+ ion.
Angle: 107.
Explain why the AsCl4(+) ion has a bond angle of 109.5.
AsCl4(+) has 4 bonded pairs of electrons. They repel equally, giving a bond angle of 109.5. The shape of the molecule is Tetrahedral.
Shape of NHF2?
Trigonal Pyramidal.
State the strongest type of Intermolecular force in Methane (CH4).
Van der Waals.
State the strongest type of Intermolecular force in Ammonia (NH3).
Hydrogen Bonding.
Suggest why Titanium can be hammered into different shapes.
Layers of atoms slide over one another.
Deduce the empirical formula of Graphane.
CH.
Why does Iodine sublime?
The weak Van der Waals forces between the molecules are easily overcome.
Why do Simple Covalent Compounds have LOW boiling and melting points?
The covalent bonds within the molecules are strong but the forces of attraction between the molecules are weak (VdW).
Simple Covalent Compounds are insoluble in water but soluble in…
Organic substances.
The element with the larger electronegativity in a polar compound will be the…
Delta minus end.
Why is Hydrogen Chloride a polar bond?
Chlorine is more electronegative than Hydrogen so it withdraws electron density from the covalent bond. The molecule has a dipole, a pair of separated charges of opposite signs.
Why is CO2 non polar?
The two dipoles cancel each other out because they act in opposite directions. There is no net dipole.
Explain why Boron Trifluoride molecules are non - polar but Water molecules are polar.
Boron Trifluoride has three dipoles that cancel each other out to leave no net dipole. The three atoms in water do not lie in a straight line, so it’s two dipoles do not cancel each other out leaving a net dipole.
Are polar molecules usually symmetrical or asymmetrical?
Asymmetrical. Eg: Bent Planar / Trigonal Pyramidal
