Bonding And Structure Flashcards
What is ionic bonding?
The strong electrostatic forces of attraction between oppositely charges
How are positive ions formed?
When metals lose electrons
How are negative ions formed?
When non-metal ions gain electrons
What are 3 properties of ionic compounds such as sodium chloride?
- Regular structure
- Cubic shape
- Giant repeating pattern
Why do most ionic compounds dissolve in water?
Since water molecules are polar, they can attract the positive and negative ions and break up the structure
When can ionic compounds conduct electricity and how?
When molten or dissolved in an aqueous solution as the ions are free to move around
Why do ionic compounds have high melting points?
There are many strong electrostatic forces between oppositely charged ions. And so lots of energy is needed to overcome these forces
Why are ionic compounds brittle?
When struct with a hammer, the layers slide and you get positive ions aligning with other positive ions, and the same happens with negative ions. They repel and the structure breaks apart
How does the size of the ion affect the strength of the ionic bond?
The bigger the charge on an ion, the stronger the electrostatic attraction between ions
How does the size of the ion (ionic radii) affect the strength of the ionic bond?
The smaller the ion, the stronger the electrostatic attraction between the ions
Why does ionic radius affect the strength of an ionic bond?
Because smaller ions can pack together more closely and more energy is required to overcome the stronger forces, so the melting and boiling points are higher
What is classified as a high charge density?
The smaller the ion and the higher the charge, the stronger the electrostatic attraction, and hence the higher the melting point
Does ionic radius increase or decrease as we go down a group?
Increase
What increases as ionic radius increases?
The number of electron shells
What is an isoelectric ion?
These are different atoms that have the same number of electrons
Why does ionic radii in isoelectric ions decrease as the atomic number increases?
Radius decreases as the attractive force from the nucleus increases (there are more protons). This pulls in the outer electron shell more
What shows as evidence for charged particles?
Electrolysis of copper (II chromate (VI) on wet filter paper
What happens in the electrolysis of green copper(II) chromate(VI)?
- The positive Cu2+ ions move towards the negative cathode, and you can see the blue solution move
- The negative CrO4 2- ions move towards the positive anode, and you can see the yellow solution move
What is covalent bonding?
The sharing of outer electrons in order for atoms to gain a full outer shell
What kind of attraction is there between covalent molecules?
An electrostatic attraction between the shared electrons and the positive nucleus
What kind of bonds exist between covalent molecules?
Single, double and triple bonds
What are dative or coordinate bonds?
When one atom donates 2 electrons
How can we symbolise coordinate (dative) bonds?
By using an arrow
How is bond enthalpy linked to the length of the bond?
The shorter the bond, the higher the bond enthalpy
