Bonding physical chemistry Flashcards
What forces hold the positive ions and negative ions together in ionic compounds
Electrostatic forces
What is a molecule
A group of atoms held together by covalent
Within a molecule how are covalent bond within atoms held together
By electrostatic attraction that occurs between the nuclei and the shared electrons
What are the 3 types of bonding
Ionic
Covalent
Metallic
What is a double bone
When four electrons are shared
Why do substances composed of molecules (solids,liquid, gas) have low melting points
This is due to the weak attraction between molecules so not a lot of energy is needed to separate them
Why do substances composed of molecules (solids,liquid, gas) have low melting points
This is due to the weak attraction between molecules so not a lot of energy is needed to separate them
Why are molecules poor conductors of electricity
As they are neutral due to them not having any charged particles
What is dative covalent bonding
It’s when in covalent bond one atom will supply both electrons
What must happen for dative covalent bonding to occur
The atom supplying the electrons has a lone pair of electrons and has a full outer shell
The atom receiving the electrons is electron efficient and dosent have a filled outer shell
What is a lone pair of electrons
Electrons that aren’t involved in the covalent bond
On a diagram how are dative covalent bonds represented
By an arrow
What is the structure of metals
It’s positive ions which form a lattice and they exist in a sea of delocalised electrons
In metals what do the outer layers of atoms do
The outer layers of atoms merge
What is the amount of deloclasied electrons dependant on
The amount of deloclasied electrons is dependant on the amount of electrons lost by each metal atom
Why do metals contain such large structures
As the metallic bonding spreads throught the metal
Name the properties of metals
Strong
High melting points
Malleable
Good conductors of heat and electricity
Why are metals such good conductors of heat
The sea of electrons have high thermal conductivites
The ions are closely packed together so when heated they vibrate vigrously and enegry spreads throughout the metal as a result
What does the strength of the metallic bond dependant on
The size of the ion and it’s charge
How does the charge of the ion make metallic bond strong
As it means that there are more deloclasied electrons and so a stronger electrostatic attraction occurs between the ions and electrons
How does ion size make a strong metallic bond
If the ion size is smaller the electrons become closer to the positive nucleus and this makes the bond stronger
What two things within a metal gives it a high boiling point and melting point
It’s has a large structure and the
strong attraction between the metal ions and the electrons
What does ductile mean
Layers slide over each other
What is Electro negativity
The power of an atom to attract electron density in a covalent bond to it’s self
What factors effect electron negativity
Nuclear charge
The shielding of nuclear charge by electron in it’s inner shell
The distance between the nucleus and the outer shell of electrons
Why does electron negativity increase across a period
This is because the nuclear charge increases so the attraction of the nucleus to the outer shells is strong
Going up a group why does electron negativity increase
This is due to there being less shielding From the inner electrons as the atoms gets smaller
What is polarity of a covalent bond
It’s when atoms that are bonded covalently have unequal distributed number of electrons
What are polar covalent bonds
When atoms are bond covalently have an uneven distribution of electrons
What can Increase the polarity of covalent bonds
The greater the difference in electro negativity
When two different atoms are bonded covalently how are the electrons spread
They spread to the atom that is most electronegative
What are the 3 types of intermolecular bonds
Van der vaals
Dipole-dipole
Hydrogen bond