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.
The Earth's rotation has no relation to the phases of the moon.
Like everything else in the sky, the moon rises in the east just like the stars, planets, and the sun.
Answer:
Humus, which ranges in colour from brown to black, consists of about 60 percent carbon, 6 percent nitrogen, and smaller amounts of phosphorus and sulfur. As humus decomposes, its components are changed into forms usable by plants.
samira-
The answer is B the flow of electrons through a substance
The <u>Mole</u> is the SI unit that expresses the amount of substance.
Mole is defined as - The mole is the amount of substance containing the same number of entities as there are in the 12 grams of Carbon - 12.
Mole is denoted by using symbol mol.
Mole = 6.022 x 10²³ elementary entities.
These number of elementary entities in 1 mole is equal to or called as an Avogadro's number. Mole is equal to 6.022 x 10²³ because this number of entity is same as in exactly 12 g of carbon-12.
It is a very important SI unit of measured which is used by the chemists. Moles are used in measuring in small or tiny things such as atoms, molecules and the other tiny particles.
To learn more about the mole concept,
brainly.com/question/28498715
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