Intramolecular Bonding

Question 1

Difinition (Intramolecular force)

Answer 1

The forces of attraction which hold an individual molecule together (eg. ionic and covalent bonding)

Question 2

octet rule ?

Answer 2

When atoms bond together, they attain the stable structure of having eight electrons in the outer shell of their atoms.
When atoms have eight electrons in the outermost shell they are chemically stable.

Question 3

1. Ionic bond

Answer 3

electrical attraction between the oppositely charged ions which are produced when electrons are transferred(moved) from one atom to another.

In general, metals interact with non-metals to form ionic bonding.
Metals tend to lose their electrons, falling back to their inner octet, becoming smaller, forming positive “cations” (positively charged)
Nonmetals tend to gain electrons, filling up their current energy levels, becoming larger, forming negative “anions”. (negatively charged)

Question 4

Ionic Lattice Packing

Answer 4

A crystal of NaCl consists of unit cells tacked together to form a lattice. (each sodium ion is surrounded by 6 chloride ions/each choloride ion is surrounded by 6 sodium ions)
The ions are held together by the attraction of their opposite charges -electrostatic forces (very strong).

Question 5

properties of Ionic compounds

Answer 5

1/ High melting and boiling points(they are not unstable) - solids at room temperature. A great deal of energy is needed to break down the lattice structure bc the ions are attracted together by electrostatic forces. The structure must therefore be heated to a high temperature before it melts.

2/ Soluble in water - water contains molecules that have one end positively charged and the other end negatively charged (dipole). Water is polar solvent and tends to dissolve ionic compounds.

3/ conduct electricity when molten or in aqueous solution - In order for a substance to conduct electricity, it must possess charged particles that can move. Solid ionic compounds don’t conduct electricity ( the ions are held firmly by strong electrostatic forces and cannot move.) When the substance is melted in water, the ions move freely and can carry an electric current. An aqueous solution, or melt, of an ionic substance that behaves in this way, is called an electrolyte.

4/ ionic crystals shatter easily - When a force is applied to the crystal, the layers of ions in the crystal structure can ‘slip’ so that similarly charged ions are next to one another. the like charges of the ions repel one another and the crystal structure shatters.

Question 6

Covalent Bonding

Answer 6

involves sharing of pairs of electrons between two or more atoms to achieve the stable electronic configuration of a noble gas. There is no electron transfer hence there are no charged particles.
Once the electrons are involved in the covalent bond there is no way to distinguish which electron comes from which atom

Question 7

properties of Covalent Compounds

Answer 7

1/ Low melting points and boiling points - they are often liquids or gases at room temperature (ex: O2,H2O,N2). The molecules are not attracted towards each other by strong electrostatic forces - so they are pulled apart at relatively low temperatures. The forces that attract molecules together (the intermolecular forces) are called van derwaals’ forces and are relatively weak.

2/ Low-soluble in water -
(covalent compounds tend to dissolve readily in non-polar organic solvents, such as benzene, which also contain covalent molecules)
Do not contain ions and therefore do not mix so readily with water molecules.

3/ Do not conduct electricity - Covalent compounds cannot conduct electricity because they do not contain ions.

Question 8

why Electronegativity increases across a period

and decreases down a group?

Answer 8

because of increasing nuclear charge and decreasing atom radius.
because of increasing increasing atomic radius and shielding effect.

Question 9

non-polar covalent

Answer 9

0.0 - 0.4
Bonding electrons shared equally between two atoms. No charges on atoms.
This happens when both atoms are the same, or have very similar electronegativity values.
H2, O2, N2, Cl2, F2, Br2, I2 (diatomic)
CH4

Question 10

Polar Covalent Bonds

Answer 10

> 0.4 - 1.9
Bonding electrons shared unequally between two atoms. Partial charges on atoms.
The more electronegative atom will pull harder and acquire a slight negative charge.
The less electronegative atom will pull less and acquire a slight positive charge.
This is donated by a delta.
HCl , HF

Question 11

Ionic Bonding,

Answer 11

> = 2.0
Complete transfer of one or more valence electrons.
Full charges on resulting ions.
NaCl

Question 12

Is Aluminium metal or non-metal?

Answer 12

metal (은박지 생각)

Question 13

H2 전기음성도 관련해서 설명

Answer 13

none of the atoms is going to have a greater pull on the electrons from the shared pair (electrons are shared equally)

Question 14

H-Cl 전기음성도 관련해서 설명

Answer 14

electrons are shared unequally Cl is going to pull the electron towards itself.
- higher electronegativity value means that the atom/element can pull the e- from the covalent bond towards itself.

Question 15

Is Hydrogen metal or non-metal?

Answer 15

non-metal

Question 16

Metallic bonding

Answer 16

Metallic bonding is a type of chemical bonding that rises from the electrostatic attractive force between conduction electrons (in the form of an electron sea of delocalised electrons) and positively charged metal ions.

It is produced when electron orbitals overlap and all electrons are shared between atoms –“sea of electrons”

Question 17

Dative bonding (definition)

Answer 17

Covalent bonds are sometimes formed between two atoms when one of the atoms provides both of the shared electrons.

The two electrons that one atom donates for sharing are called a lone pair of electrons.

Question 18

Dative bond examples (2)

Answer 18

hydronium ion : H3O+
ammonium ion : NH4+
(좌우 charge 확인)*

Question 19

Transition metal complexes (complex ion)

Answer 19

Transition metal ions form coordination complexes because they have empty valence-shell orbitals that can accept pairs of electrons from a ligand.

Ligands must contain at least one pair of nonbonding electrons that can be donated to a metal ion.

The number of atoms directly attached to the central metal atom is called the coordination number.

Question 20

Electronegativity (definition)

Answer 20

A measure of the attraction of an atom of an element for the shared pair of electrons in a covalent bond.

Question 21

C-F vs H-Cl

F has higher electronegativity value than Cl WHY?

Answer 21

[1] F is going to pull harder the e- towards itself

[2] F has higher nuclear charge than Cl so it is going to attack the electrons harder than Cl