Answer:
1) Ca: [Ar]4s²
2) Pm: [Xe]6s²4f⁵
Explanation:
1) Ca:
Its atomic number is 20. So it has 20 protons and 20 electrons.
Since it is in the row (period) 4 the noble gas before it is Ar, and the electron configuration is that of Argon whose atomic number is 18.
So, you have two more electrons (20 - 18 = 2) to distribute.
Those two electrons go the the orbital 4s.
Finally, the electron configuration is [Ar] 4s².
2) Pm
The atomic number of Pm is 61, so it has 61 protons and 61 electrons.
Pm is in the row (period) 6. So, the noble gas before Pm is Xe.
The atomic number of Xe is 54.
Therefore, you have to distribute 61 - 54 = 7 electrons on the orbitals 6s and 4f.
The resultant distribution for Pm is: [Xe]6s² 4f⁵.
Explanation:
Charges on both magnesium and oxygen is 2. Though opposite in sign, they have equal charges so, both of them will be cancelled by each other.
As a result, formula of magnesium oxide is MgO and not 
.
The student write the equation as 
, it is not correct.
Therefore, given equation will be balanced as follows.
Since, number of atoms on both reactant and product side are equal. Hence, this equation is completely balanced.
The ch4 molecule exhibits hydrogen bonding.
This statement is false. A CH4 molecule do not have a hydrogen bonding instead it has dipole dipole attraction.
Hydrogen bonding occurs when a hydrogen atom is covalently bonded to an N, O, or F atom.
This would be a true statement. A hydrogen bond is present when an atom of hydrogen shares electrons with O, N or F atom.
A hydrogen bond is equivalent to a covalent bond.
This is a false statement. A hydrogen bond is an intermolecular force of attraction while covalent bond is a intramolecular force. So, they would mean different things.
a hydrogen bond is possible with only certain hydrogen-containing compounds.
This would be true. Without the presence of an hydrogen atom definitely there would be no hydrogen bond.
a hydrogen atom acquires a partial positive charge when it is covalently bonded to an f atom.
This would be true since a HF is a polar molecule.
The value 6.0 x 10^3- 2.3 × 10^3 in scientific notation is 3.7 × 10^3.
<h3> What is scientific notation?</h3>
Scientific notation is a way to write very large or very small numbers so that they are easier to read and work with.
You express a number as the product of a number greater than or equal to 1 but less than 10 and an integral power of 10 .
<h3>Why it is used? </h3>
There are two reasons to use scientific notation.
- The first is to reveal honest uncertainty in experimental measurements.
- The second is to express very large or very small numbers so they are easier to read.
Given,
= 6.0 x 10^3- 2.3 × 10^3
= (6.0 - 2.3) × 10^3
= 3.7 × 10^3
Thus, we find that the value 6.0 x 10^3- 2.3 × 10^3 in scientific notation is 3.7 × 10^3.
learn more about scientific notation :
brainly.com/question/18073768
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