Microscopic world 2

Question 1

why some molecules are in trigonal pyramidal

Answer 1

repulsion between electron pairs

Question 2

why radicals have high reactivity

Answer 2

it doesn’t have stable octet

Question 3

why water will deflect towards charged rod

Answer 3

water is a polar molecule

Question 4

explain the formation of hydrogen bonding in hydrogen fluoride

Answer 4

N/O/F is a highly electronegative element

H-F/H-O/H-N covalent bond is very polar

Question 5

why ethyl ethanoate is a better solvent than water for dissolving cinnamaldehyde.

Answer 5

cinnamaldehyde is a non-polar compound that can dissolve in a relatively non-polar organic solvent like ethyl ethanoate. However, water is a polar solvent.

Question 6

Explain why the density of ice is lower than that of water

Answer 6

The attraction between water molecules is predominately hydrogen bond
Hydrogen bond is directional. In ice, the water molecules have a tetrahedral arrangement and packed in an open structure.
In liquid water, the water molecules have relative motions and this leads to the collapse of the open structure. The molecules become more closely packed. So liquid water has higher density than ice.

Question 7

VSEPR theory states that

the theory is out syl but better rmb it also :)

Answer 7

electron pairs in the outermost shell of the central atom in a molecule will stay as far as possible

Question 8

BeCl2 shape?

Answer 8

linear

its a covalent molecule

Question 9

meaning of octet rule

Answer 9

all atoms tend to achieve the stable electronic arrangement of a noble gas by sharing or transferring electrons

Question 10

definition of dative covalent bond

Answer 10

it is a covalent bond in which both electrons in the bond are donated by one atom

Question 11

definition of electronegativity

Answer 11

the ability of an atom to attract bonding electrons in a covalent bond

Question 12

electronegativity sequence for common atoms

Answer 12

F>O>N~Cl>Br>C>H~P

Question 13

trend of atomic size through a period

Answer 13

more outermost electrons

small atomic size in the same period

Question 14

hydrogen bond definition

Answer 14

its a strong intermolecular force between a H atom covalently bonded to a small highly electronegative atom in one molecule and the lone pair electrons on a small highly electronegative atom in another molecule

Question 15

what is viscosity

Answer 15

the resistance of a liquid to flow

depends on intermolecular force

Question 16

what is crystal

Answer 16

it is a solid material whose constituent atoms/molecules are arranged in an orderly repeating pattern extending throughout the material
including
metallic crystal
ionic crystal 
covalent crystal
molecular crystals

Question 17

why ice is less dense than water

Answer 17

the intermolecular attraction in both ice and liquid water is mainly hydrogen bond
In solid ice, each H2O molecule is surrounded by four other H2O molecules tetrahedrally, this results in a regular open network structure.
when ice melts, the open structure collapse. Molecules can be packed closely together in liquid water than in ice,
Therefore, ice has a smaller density than water.

Question 18

what is allotropes

Answer 18

allotropes are different structural form of the same element

Question 19

total number of lone pair electrons in a PCl3 molecule is 10

T/F

Answer 19

T
(scl mock)
inner shell dont need to be calculated