8 valence electrons means that the element is stable. When we hear stable, we know the group to look at! Noble gases all have 8 valence electrons making them stable and have a full octet.
Here are some:-
Krypton
Argon
Neon
Answer:
C. C and Pb
Carbon and Lead being in the same group.
Answer:
He
Explanation:
A molecule is the smallest physical unit of a substance that can exist independently, consisting of 2 or more atoms chemically combined
He is one atom of Helium
Answer:
m = 0.5556 mol/kg
Explanation:
The molality of any solution is calculated using the following expression:
m = moles solute / kg solvent (1)
So in order to calculate the molality of this solution, we need to calculate the moles of the glucose using the expression:
n = mass / molecular weight (2)
The molecular weight of glucose, can be calculated using the molecular mass of the atoms in the glucose:
C = 12 g/mol; H = 1 g/mol; O = 16 g/mol
the molecular weight is:
MW = (12*6) + (12*1) + (6*16) = 180 g/mol
Then, the moles of glucose:
moles = 50 / 180 = 0.2778 moles
The solvent in this case is water, and 500 g of water is 0.5 kg of water, so the molality is:
m = 0.2778 / 0.5
m = 0.5556 mol/kg
Answer:
Ionic size increases from top to bottom within the group.
Explanation:
- Ions are formed when neutral atoms of elements gain or lose electron(s).
- The ionic radius is the distance from the nucleus of an ion to the outermost energy level.
- The ionic size or radius increases down the group as the number of energy level increases.
- Therefore, an ion of an element lower in the group will be larger than the ion of an element higher in the group.
- For example, an ion of potassium, K+, is larger in size compared to the ion of sodium, Na+ since K+ has more energy levels than Na+.
