Answer:
For O: atomic number = 8 # neutrons = 8
For Al: atomic mass = 27, # electrons = 13
Answer:
Various limitations of Mendeleev's periodic table are:-
Position of hydrogen - he couldn't assign a correct position to hydrogen as it showed properties of both alkali and halogens .
Position of isotopes - he considered that the properties of elements are a function of their atomic masses. Hence isotopes of a same element couldn't be placed.
In the d-block , elements with lower atomic number were placed before higher atomic number.
Explanation:
Answer:
Explanation:
The question is not complete, the cmplete question is:
Identify one type of noncovalent bond present in each solid.
1) Table salt (NaCl) 2) Graphite (repeating)
a. hydrogen bonds
b. ionic interactions
c. van der Waals interactions
d. hydrophobic interactions
Answer:
1) Table salt
b. ionic interactions
Ionic bond are formed between atoms with incomplete outermost shell. Some atoms add electrons to their outermost shell to make the shell complete hence making it a negative ion while some atoms loses their electron to make the outermost shell complete becoming a positive ion. In NaCl, sodium (Na) has 1 electron in its outermost shell which it transfers to Cl which has 7 electrons in the outermost shell. Hence after the bonding the outermost shell of the atoms become complete.
2) Graphite
c. Van Der Waals interaction
Van der waal forces are weak interaction between molecules that exist between close atoms. Carbon atoms in graphite planes have covalent bond, these graphite planes are known as graphenes. Bonds between graphenes are very weak and are van der waals forces.
The structure will be:
H₃C-CH₂-CH=CH-CH₂-CH₃
This class of compounds is known or referred to as alkenes. Alkenes are unsaturated hydrocarbons that contain a carbon-carbon double bond. The present of this double bond alters the properties of alkenes rom alkanes.
<u>Answer:</u> The correct statement is low temperature only, because entropy decreases during freezing.
<u>Explanation:</u>
The relationship between Gibb's free energy, enthalpy, entropy and temperature is given by the equation:
Where,
= change in Gibb's free energy
= change in enthalpy
T = temperature
= change in entropy
It is given that freezing of methane is taking place, which means that entropy is decreasing and 
is becoming negative. It is also given that the reaction is an exothermic reaction, this means that the is also negative.
For a reaction to be spontaneous, must be negative.
![-ve=-ve-[T(-ve)]\\\\-ve=-ve+T](https://tex.z-dn.net/?f=-ve%3D-ve-%5BT%28-ve%29%5D%5C%5C%5C%5C-ve%3D-ve%2BT)
From above equations, it is visible that will be negative only when the temperature will be low.
Hence, the correct statement is low temperature only, because entropy decreases during freezing.
