Bonding: Ionic+ Covalent+ Metallic 2.2.1, 2.2.2 Flashcards
What is the structure of a metal
Giant Metallic Lattice
Types of particles involved in metallic bonding
Positive ions and delocalized electrons
Metallic Bonding= High or Low Melting and Boiling point ?
High Melting and Boiling point
Metallic Bonding: Conducts Electricity?
Yes, delocalized electrons are free to move and can carry charge
Giant metallic Lattice= Dissolves in water?
Doesn’t dissolve in water
Giant metallic Lattice= Dissolves in Covalent Solvents?
No
In metallic bonding what is special about the delocalized electrons
-delocalized electrons- not attached to one specific atom, they are free to move
How would you describe the Giant Metallic Lattice
lattice of regularly spaced positive ions, fixed in position surrounded by delocalized electrons
In metallic bonding are the metal ions able to conduct electricity
A metal contains delocalised electrons which are free to move, so it can conduct electricity in solid and molten states
How are the Positive metal ions in Metallic bonding attracted to each other and how does this affect the melting or boiling point
Electrostatic forces of attraction between positive ions and negative delocalized electrons.
A large amount of energy is needed to overcome the electrostatic forces so the melting point is high
What would affect the melting and boiling point in a metallic bonding
Metals with a high charge density (small ionic radius, high charge) have stronger electrostatic forces between positive ions and negative electrons so more energy is needed to overcome the strong electrostatic forces of attraction therefore increasing the m.p. and b.p.
What structure does Ionic bonding form
Giant Ionic Lattice
What types of Particles join to make ionic bonding
Positive metal ions and Negative metal ions
In Ionic Bonding is there high or low melting and boiling point
High melting + boiling point
In Ionic bonding do the ions conduct electricity
Not when solid but yes when Molten, because the negative ions are in a fixed position and are not free to move so cannot carry charge
In ionic bonding are the ions able to dissolve in water
Mostly
In Ionic bonding are the ions able to dissolve in Covalent Solvents
No
Give an example of a giant ionic lattice
NaCl
Sodium Chloride
What does the compound in ionic bonding consist of
Ions- cations+ anions, metals and non-metals
Compound contains metal + non-metal unless it contains an ammonium ion
What is an ion
A charged particle
What types of ions are there
They can be atomic ions e.g. Cl-, Na+
-Or molecular ions e.g. NO3 -, SO4 2-
Metals form…
Non-metals form…
Positive cations and negative anions attract and …
-metals form positive ions- cations
-non-metals form negative ions- anions
-positive cations and negative anions attract and form a giant ionic lattice structure
When do ions occur
When an element or molecule have either more electrons than protons or fewer electrons than protons
Why do ionic compounds not conduct electricity when solid, but do conduct electricity when molten or dissolved in water?
-When solid, the ions are in a fixed position in a giant ionic lattice and are not free to move. The solid does not conduct electricity
- When molten or dissolved in water, the ions are free to move and conduct electricity
What is ionic Bonding
An Ionic bond is the electrostatic force of attraction between oppositely charged ions
How are the ions arranged in a Ionic solid
In an ionic solid the ions are arranged in a regular 3D pattern called giant ionic lattice
Typical Physical Properties of Ionic Compounds
High melting points- strong electrostatic forces of attraction between oppositely charged ions int he lattice
Does not Conduct electricity- ions are in a fixed position+ are held together tightly and are not able to move therefore cannot carry charge
-Good conductor of electricity when in solution or molten- ions are free to move and therefore can carry charge when
-Usually soluble in aqueous solvents
Which elements are so stable they exist as single atoms
Noble gases
What can we say about the outer shells of noble gases
They have full outer shells and are therefore stable
What 2 factors need to be considered when trying to work out the charge density of the ions
The charge of the ion and the size of the ion
What 2 factors give an ion a high charge density (a high positive or negative charge per unit volume)?
-The ion has a small radius
-The ion has a high charge
Using the periodic table explain what happens to the ionic radius, for when you are trying to work out charge density
Ionic radius decreases across a period, and increases down a group
Do ionic compounds have high or low melting and boiling points? Explain why.
High melting and boiling point because there is a strong electrostatic force of attraction between the oppositely charged ions , this needs a lot of energy to overcome the ionic bonds and separate the ions
How does Charge density (amount of charge per unit volume) of an ion affect the melting or boiling point of the ionic compound?
An ion with a high charge density (high charge, small ionic radius) will form stronger ionic bonds. More energy will be needed to overcome the electrostatic attraction between ions to separate the ions. The melting or boiling point will be higher.
The strength of the ionic bond increases when the…
charge on the ion increases
As we move across a period the…
ions get smaller
As we move down a group…
the ions get bigger
What happens to the strength of the ionic bond when the ions get smaller
When the ions get smaller the ionic bond becomes stronger because there is a higher charge per the ions volume so it has a higher charge density, therefore stronger electrostatic forces of attraction between the bonds which need more energy to overcome the ionic bond and separate the ions
What has a higher melting and boiling point, Calcium Chloride or Calcium Fluoride
Fluorine is a smaller ion than chlorine and has the same charge however because its a smaller ion and has a high charge density it will take more energy to overcome the ionic bond and separate the ions hence Calcium Fluoride has a higher melting point than Calcium Chloride
What 2 processes do we have to consider when an ionic compound dissolves?
-Energy taken in by the compound to overcome the electrostatic attractions (ionic bonds) between ions in the lattice, and separate the ions
-Energy given out when intermolecular attractions are made between an ion and surrounding polar water molecules
Why is it so hard to predict the solubility of an ionic compound
-If an ion has a high charge density, the electrostatic attractions will be stronger
SO
More energy will be needed to break the ionic bonds in the lattice
BUT also
-More energy will be given out when intermolecular attractions are made with water molecules
What is the structure of covalent compounds
Simple molecular structure
Types of particles involved in covalent bonding
Non-metal atom and a Non-metal atom
Do covalent compounds have high or low melting and boiling points
Low melting and boiling points, weak intermolecular forces
Do covalent compounds conduct electricity
No they do not have delocalized electrons or any ions to move freely and carry charge
Can covalent compound dissolve in water
No
Can covalent compounds dissolve in covalent solvents
Yes
What is a covalent bond
Electrostatic force of attraction between the shared pair of negatively charged electrons and the 2 positively charged nuclei of the non-metal atoms
What are lone pairs of electrons
Lone pair= pairs of electrons occupying orbital in an atom or molecule but not directly involved in bonding
What are bonding pairs
Bonding pair= electron pairs of electrons being shared between atoms or molecules
What are dative covalent bonds
Covalent bonds whereby all the shared pairs of electrons come from one atom
What are molecules
- small groups of non metal atoms
- Can be elements or compounds
- covalently bonded
What is considered a perfect covalent bond
When the atoms sharing the pair of electrons have the same radii and the same nuclear charges. The ‘pull’ on the pair of electrons is equal and they are equally shared e.g. H2 O2, N2
What is a polar molecule
The atoms sharing the pair of electrons have different radii or different nuclear charges. The shared electrons are more attracted to one of the nuclei- therefore one of the atoms gets a partial negative charge- delta minus
Define electronegativity
The relative ability of an atom to attract the pair of electrons in a covalent bond is called its electronegativity.
How can we distinguish electronegativity on a periodic table
Electronegativity increases across a period and up the group - Fluorine is the most electronegative element
