Elements in the same group have the same amount of electrons.
Elements in the same period have the same amount of atomic orbits.
Hope this helps!
Answer:
An acid is a substance that donates protons (in the Brønsted-Lowry definition) or accepts a pair of valence electrons to form a bond (in the Lewis definition). A base is a substance that can accept protons or donate a pair of valence electrons to form a bond. Bases can be thought of as the chemical opposite of acids.
Answer is (3) - ratio of neutrons to protons.
Isotopes are the atoms which have same atomic number but have different number of neutrons of same element.
Atomic nucleus can be stable or unstable. The stability of isotopes is based on neutron/ proton ratio. Unstable nucleus tries to become stable by emitting radiations.
First, we divide the number of atoms of silicon given in the problem above by Avogadro's number 6.6022 x10^23. This will give us the number of moles of silicon. Then, we multiply the number of moles by the molar mass of silicon.
number of moles = (3.6 x 10^20 atoms/6.022x10^23 atoms) = 5.97x10^-4 moles
Then, multiplying by the molar mass
(5.97x10^-4 moles)(28.0855 g/mol) = 0.017 grams
Answer:
The percentage by mass of element X is 25 %.
The percentage by mass of element Y is 75 %
Explanation:
X + Y ⇒ XY
3.5 g of element X + 10.5 g of element Y = 14g in total
⇒Element X : 3.5g / 14g = 0.25 ⇒ x 100 % = 25 %
⇒Element Y : 10.5 / 14 = 0.75 ⇒ x 100 % = 75 %
The percentage by mass of element X is 25 %.
The percentage by mass of element Y is 75 %
