JJ Thomson discovered electrons using the cathode ray. Electrons are negatively charged particles that orbit around the nucleus of an atom. Finding out that there was a negative charge to balance out the positive charge. This later helped develop Hund's Rule and the Pauli Exclusion Principle.
Answer:
Valence electrons
Explanation:
In a period, the number of valence electrons increases (mostly for light metal/elements) as we move from left to right side
<h2><u>Answer:</u></h2>
The correct answer is A) 1.04 mol Cu
{65.8 g / 63.55 g/mol}
= 1.04 mol Cu
Explanation:
In 63.55 g of copper metal there are 1 m
o
l of C
u atoms. By dividing the mass of Cu and molar mass, we can easily get the number of moles.
If it is cooled the motion of the particles decreases as they lose energy.
This uses the concept of freezing point depression. When faced with this issue, we use the following equation:
ΔT = i·Kf·m
which translates in english to:
Change in freezing point = vant hoff factor * molal freezing point depression constant * molality of solution
Because the freezing point depression is a colligative property, it does not depend on the identity of the molecules, just the number of them.
Now, we know that molality will be constant, and Kf will be constant, so our only unknown is "i", or the van't hoff factor.
The van't hoff factor is the number of atoms that dissociate from each individual molecule. The higher the van't hoff factor, the more depressed the freezing point will be.
NaCl will dissociate into Na+ and Cl-, so it has i = 2
CaCl2 will dissociate into Ca2+ and 2 Cl-, so it has i = 3
AlBr3 will dissociate into Al3+ and 3 Br-, so it has i = 4
Therefore, AlBr3 will lower the freezing point of water the most.
