Answer is: another name for groups of elements is family.
There are 18 numbered groups in the periodic table.
The elements in a group have similar physical or chemical characteristics and some groups have a specific name, for example group 17 (the halogens).
Elements in the group have the same number of valence electrons, for example, chemical elements in group 15 of the periodic table have neutral atom with a valence electron configuration of ns²np³.
Answer:
D = Mass = 42.6 g
Explanation:
Given data:
Mass of phosphorus react = 33 g
Mass of oxygen needed = ?
Solution:
Chemical equation:
4P + 5O₂ → 2P₂O₅
Number of moles of phosphorus:
Number of moles = mass/molar mass
Number of moles = 33 g/ 30.97 g/mol
Number of moles = 1.065 mol
now we will compare the moles of phosphorus and oxygen.
P : O₂
4 : 5
1.065 : 5/4×1.065 = 1.33mol
Mass of oxygen needed:
Mass = number of moles × molar mass
Mass = 1.33 mol × 32 g/mol
Mass = 42.6 g
Thus, 43.6 g of oxygen needed to react with 33 g of phosphorus.
Answer:
The correct answer is - 3.012×10^23 molecules
Explanation:
The number of molecules is present in any mole of an element or compound are the same. To find the molecules you need to multiply the number of the moles of the compound by Avogadro's number:
Moles are calculated from the molecular weight, for AlF3
= 26.98 + 3×19
= 26.98 + 57
= 83.98
Then moles in 42 grams:
= 42/83.98
= 0.5001190 moles
Now the number of molecules = moles*Avogadro's number
= 0.500110×6.022×10^23
= 3.011×10^23 molecules
