Answer:
The periodic table is useful today for finding out all the elements that exists on Earth. The elements there can be used to write down chemical formulas, calculate things like molar mass/atomic mass of each element, atomic number for each, number of valence electrons each element has, the oxidation number for each, etc. Lastly, it can be used to predict the properties of elements yet to be discovered.
Explanation:
Hope it helped!
<span>1. The evolution of energy
2. the production of a gas
3. the formation of a precipitate
4. color change
</span>
Answer:
1x10⁻¹²
Explanation:
- Cu₂S(s) ⇌ 2Cu⁺(aq) + S²⁻(aq)
At equilibrium:
The equilibrium constant for the the reaction can be written as:
[Cu⁺] is squared because it has a stoichiometric coefficient of 2 in the reaction. <em>Cu₂S has no effect on the constant because it is a solid</em>.
Now we can <u>calculate the equilibrium constant</u>:
- Keq = (1.0x10⁻⁵)² * 1.0x10⁻² = 1x10⁻¹²
These are three questions and three complete answers
Answer:
a) Cr²⁺: [Ar] 4s² 3d²
b) Cu²⁺: [Ar] 4s² 3d⁷
c) Co³⁺: [Ar] 4s² 3d⁴
Explanation:
<u>a) Cr²⁺</u>
- Number of elecrons of the neutral atom: 24
- Number of electrons of the ion: 24 - charge = 24 - 2 = 22.
Fill the orbitals in increasing order of energy. Using Aufbau's rules the order is: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ .....
Hence, for 22 electrons you get:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d²
- Abbreviated notation: since the last complete level is the number 3s² 3p⁶, you use the noble gas of the period 3, which is Ar, and the configuration is:
[Ar] 4s² 3d²
<u>b) Cu²⁺</u>
- Number of elecrons of the neutral atom: 29
- Number of electrons of the ion: 29 - charge = 29 - 2 = 27.
Fill the orbitals in increasing order of energy. Using Aufbau's rules the order is: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ .....
Hence, for 27 electrons you get:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁷
- Abbreviated notation: since the last complete level is the number 3s² 3p⁶, you use the noble gas of the period 3, which is Ar, and the configuration is:
[Ar] 4s² 3d⁷
<u>c) Co³⁺</u>
- Number of elecrons of the neutral atom: 27
- Number of electrons of the ion: 27 - charge = 27 - 3 = 24.
Fill the orbitals in increasing order of energy. Using Aufbau's rules the order is: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ .....
Hence, for 24 electrons you get:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁴
- Abbreviated notation: since the last complete level is the number 3s² 3p⁶, you use the noble gas of the period 3, which is Ar, and the configuration is:
[Ar] 4s² 3d⁴
