Explanation:
Both Primary Key and Candidate Key are the attributes that are used to access tuples from a table. These (Primary key and Candidate key) are also can be used to create a relationship between two tables.
- A Candidate Key can be any column or a combination of columns that can qualify as a unique key in the database. Each Candidate Key can qualify as a Primary Key.
- A Primary Key is a column or a combination of columns that uniquely identify a record. The primary key is a minimal super key, so there is one and only one primary key in any relationship.
<em> The main difference between them is that a primary key is unique but there can be many candidate keys. </em>
I hope you find this information useful and interesting! Good luck!
It is like this: . You just put a circle and that is a power point
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Answer:
-
= 1
= 1
Explanation:
Argon atom has atomic number 18. Then, it has 18 protons and 18 electrons.
To determine the quantum numbers you must do the electron configuration.
Aufbau's principle is a mnemonic rule to remember the rank of the orbitals in increasing order of energy.
The rank of energy is:
1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 6p < 7s < 5f < 6d < 7d
You must fill the orbitals in order until you have 18 electrons:
- 1s² 2s² 2p⁶ 3s² 3p⁶ : 2 + 2 + 6 + 2 + 6 = 18 electrons.
The last electron is in the 3p orbital.
The quantum numbers associated with the 3p orbitals are:
- = 1 (orbitals s correspond to = 0, orbitals p correspond to = 1, orbitals d, correspond to = 2 , and orbitals f correspond to = 3)
- can be -1, 0, or 1 (from - to + )
- the fourth quantum number, the spin can be +1/2 or -1/2
Thus, the six possibilities for the last six electrons are:
- (3, 1, -1 +1/2)
- (3, 1, -1, -1/2)
- (3, 1, 0, +1/2)
- (3, 1, 0, -1/2)
- (3, 1, 1, +1/2)
- (3, 1, 1, -1/2)
Hence, the correct choice is:
- = 1
- = 1
You just need to set a reminder on your phone and try and remember
