Why are there 2 elements in the first period and 8 in the second?

Why are there 2 elements in the first period and 8 in the second?

(a) The 1st period has two elements because the 1st electron shell of an atom can take a maximum of two electrons only. The 2nd period of the periodic table has 8 electrons because the maximum no. of electrons which can be put in the 2nd shell of an atom is 8.

Why does period 1 only have 2 elements?

This is because in quantum physics, this period fills up the 1s orbital. Period 1 elements follows the duet rule, they only need two electrons to complete their valence shell. These elements can only hold two electrons, both in the 1s orbital. Therefore, period 1 can have only two elements.

Why does Period 2 and 3 have 8 elements?

Simple Answer: In the first period, the first electron shell is being filled. In the second period, the second shell is being filled. And so on. There are 8 elements in period 2 because all those elements have electrons in the second shell and no electrons in the third shell.

Why are elements in Period 2 all in period 2?

Period 2 is the first period in the periodic table from which periodic trends can be drawn. All period 2 elements completely obey the Madelung rule; in period 2, lithium and beryllium fill the 2s subshell, and boron, carbon, nitrogen, oxygen, fluorine, and neon fill the 2p subshell.

How many elements are there in the 1st and 2nd period of periodic table and why?

Period 1 has only two elements (hydrogen and helium), while periods 2 and 3 have 8 elements. Periods 4 and 5 have 18 elements.

What do all elements in Period 2 have in common?

All of the elements in a period have the same number of atomic orbitals. All of the elements in the second row (the second period) have two orbitals for their electrons. As you move down the table, every row adds an orbital. At this time, there is a maximum of seven electron orbitals.

What is dobereiner’s law of Triad?

Dobereiner law of triads states that the average of the atomic masses of the first and third element in a triad will be roughly equal to the atomic mass of the second element in that triad. He suggested that this law can be extended for other properties of elements like density.

Why is the third period contains 8 elements and not 18?

According to the 2n2 rule, the maximum number of electrons in the third period = 2 x (3)2 = 18. But, the last shell cannot accommodate more than 8 electrons so, the number of electrons in third period is 8. Hence, the number of elements is also 8.

Why does a 3f row not exist?

In the third shell, only the 3s, 3p and 3d orbitals exist, as it can hold a maximum of 18 electrons. Therefore, the 3f orbitals do not exist.

Why does 2nd period have only 8 elements?

2nd period has only 8 elements because – As we move in a period from left to right , one electron gets added in the outermost shell of the atom. In 2nd period outermost shell will be the 2nd shell. And, 2nd shell can have a maximum of 8 electrons in it, because it contains s and p subshell only.

Which of the following elements is in period 1?

Period 1 represents The first atomic shell, which has only one s orbital. The s orbital can hold a maximum of two electrons . Therefore, you have the first element in Period1, hydrogen, which has 1 electron, and the second, helium, which has 2 electrons. Hope this helps.

What is the difference between period 1 and period 2?

Period 2 is the first period in the periodic table from which periodic trends can be drawn. Period 1, which only contains two elements ( hydrogen and helium ), is too small to draw any conclusive trends from it, especially because the two elements behave nothing like other s-block elements. Period 2 has much more conclusive trends.

What are the trends in period 2 of periodic table?

Periodic trends. Period 2 has much more conclusive trends. For all elements in period 2, as the atomic number increases, the atomic radius of the elements decreases, the electronegativity increases, and the ionization energy increases.