<span>Answer:
Some metals have the ability to form differently charged ions. For example, iron can form
2
+
or
3
+
ions. If you simply gave the name iron chloride, you would not know which charge the iron ion possessed.
A Roman numeral is to indicate the charge of the iron.
Iron (
II
) means the iron has a
2
+
charge
Iron (
III
) means that the iron has a
3
+
charge
So, iron (
II
) oxide would have a chemical formula of
FeO
.
(The oxide ion has a
2
â’
charge to balance the
2
+
of the iron to form a neutral compound.)
Iron (
III
) oxide would have a chemical formula of
Fe
2
O
3
(Here you need to find the common multiple of 6, so two iron ions with a
3
+
charge will balance the charge of three oxide ions with a
2
+
charge.)</span>
Zeff is the effective nuclear charge wherein, Z resembles the number of protons in the nucleus while S corresponds to the number of non-valence electrons.
Zeff = Z - S
Silicon has 14 protons; its electron configuration is [Ne] 3s2 3p2. Its
non-valence electrons is in the n = 1 and n =2 shells. There are 2
electrons in n = 1 and 8 in n = 2, so there are a total of 10
non-valence electron.
<span><span>Z<span>eff</span></span>= 14−10= 4</span>
So, the answer is 4.
Answer: A
FeCl3 + 3 NaOH -> Fe(OH)3 + 3 NaCl
The molar mass of the M2O = 2(molar mass of M) + molar mass of oxygen
Molar mass of oxygen = 16
Therefore:
231.74 = 2(molar mass of M) + 16
215.74 = 2*molar mass of M
molar mass of M = 107.87 grams
Now, from the given formula, we can notice that the metal M is monovalnet and we know that chlorine is monovalent as well.
Therefore, the compound formed will be: MCl
molar mass of chlorine = 35.5 grams
Therefore,
molar mass of MCl = 107.87 + 35.5 = 143.37 grams
Superconductors are materials that transfer energy with no resistance. Metals are usually the best conductors.
Superconductivity is a phenomenon characterized by zero electrical resistance at below critical temperatures. Metals are the best conductors because the molecules inside them are tightly packed, which allows electricity to travel efficiently.
Water is also a good conductor because of the ions and minerals in it. However, water itself is not a conductor of electricity.
