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What is an orbital?
What is an orbital?
An orbital is a region of space where there is a high probability of finding an electron.
Explain any two of the quantum numbers
Explain any two of the quantum numbers
1. Principal quantum number: This shows the main energy level of the electron. It is denoted by the symbol,n. For a given value of n, the number of orbitals it can have it given as n2. The number of electrons that a given n can take is 2n2.

2. Azimuthal quantum number: This describes the shape of the orbital in which the particular electron is found. It is denoted by the symbol, l and has values ranging from 0 to (n-1). For n= 0,1,2,3 etc, they are designated with s,p,d,f orbitals having the shapes, spherical,dumbbell,clover shape etc.

3. Magnetic quantum number:This shows the orientation of the orbital in which that particular electron is found. It is also denoted by Ml and has values ranging from -l to +l.

4. Magnetic spin quantum number: This shows the direction of spin of the electron in it's suborbital. It has only two values i.e,+_0.5
Which of the following orbitals will first be filled filled, 3s and 3d?
Which of the following orbitals will first be filled filled, 3s and 3d?
The 3s orbital will firstly be filled before the 3d and this because, according to the Aufbau's principle, orbitals of lower energies are first filled before those of higher energies. The 3s orbital has a lower energy as compared to the 3d, hence the reason why it will be first filled.
Between K and Ca, which one has a larger size and why?
Between K and Ca, which one has a larger size and why?
K and Ca are found in the same period(2), and for atomic radius/size, it decreases across the period. Hence K has a larger size as compared to Ca because, across the period, nuclear charge increases due to the increase in electrons, screening of the valence electron by the core electrons is similar therefore the effective nuclear charge on the valence electron by the nucleus increases thereby decreasing the size of Ca more than K.
Explain why Na+ has a small size as compared to Na.
Explain why Na+ has a small size as compared to Na.
Generally, cations have a smaller size than their corresponding atom. Na+ has a small size as compared to Na because, atomic radius decreases with increasing number of shells and screening effect. Na+ has two shells whiles Na has three, hence the valence electrons in Na+ experience a stronger pull of the effective nuclear charge than that of Na, hence the small size of Na+.