> How many valence electrons does a helium atom have?
The electron configuration of Helium is simply 1s2. We see
that its outermost shell is the s shell and it contains 2 electrons, therefore
the number of valence electrons is also 2.
> What is the formula of the ion formed when potassium
achieves noble-gas electron configuration?
Potassium has a electron configuration of [Ar] 4s1. To
have an electron configuration of only [Ar] which is a noble gas, the one electron
from 4s1 should be removed, hence:
<span>K+</span>
Moles of lead(Pb) = 1.6x10^23/6.02x10^23 = 0.265 moles.
Weight of lead = moles x atomic weight of lead
= 0.265x207.2
= 54.908 grams.
Hope this helps!
Answer:
The symbol of each element is, Ne, Na, Mg, and Al.
Explanation:
Below is the list of elements that has an atomic mass of less than 19.3 u.
The atomic mass of Neon is 20.1797 u and the atomic number is 10.
The atomic mass of Sodium is 22.989769 u and the atomic number is 11.
The atomic mass of Magnesium is 24.305 u and the atomic number is 12.
The atomic mass of Aluminium is 26.981539 u and the atomic number is 13.
Here, the symbol of each element is, Ne, Na, Mg, and Al.
Answer:
The product is 1-methylcyclopentanol
Explanation:
The acid-catalyzed hydration of alkenes involves the addition of a water molecule to a C=C double bond.
H₂O + C=C ⟶ H-C-C-OH
An H atom adds to one of the C atoms, and an OH group adds to the other
This reaction follows Markovnikov’s rule — the H adds to the C atom that has more hydrogen atoms, and the OH adds to the more substituted carbon.
The steps of the mechanism are:
- The aqueous sulfuric acid generates hydronium ions
- The nucleophilic π electrons attack an H atom on the hydronium ion, forming a carbocation on the more substituted C atom.
- The lone pair electrons on a water molecule attack the carbocation , forming an oxonium ion.
- Another water molecule removes the extra proton.
The product is the alcohol with the OH group on the more substituted carbon — 1-methylcyclopentanol.
Well when the sun makes water dissaper thats usually evaporation.
The chemical changes is when the plants absorb the energy from the sunlight and convert water and carbon dioxide into sugar and oxygen gas. Physically nothing has changed. The plant still looks the sam changes occur internally these internal changes are chemical in nature.
