How many times of o are there?
2 answers:
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See the sketch attached.
<h3>Explanation</h3>The Lewis structure of a molecule describes
- the number of bonds it has,
- the source of electrons in each bond, and
- the position of any lone pairs of electrons.
Atoms are most stable when they have eight or no electrons in their valence shell (or two, in case of hydrogen.)
- Each oxygen atom contains six valence electrons. It demands <em>two</em> extra electrons to be chemically stable.
- Each sulfur atom contains six valence electrons. It demands <em>two </em> extra electrons to be chemically stable.
- Each hydrogen atom demands <em>one</em> extra electron to be stable.
H₂O contains two hydrogen atoms and one oxygen atom. It would take an extra 2 + 2 × 1 = 4 electrons for all its three atoms are stable. Atoms in an H₂O would achieve that need by sharing electrons. It would form a total of 4 / 2 = 2 O-H bonds.
Each O-H bond contains one electron from oxygen and one from hydrogen. Hydrogen has no electron left. Oxygen has six electrons. Two of them have went to the two O-H bonds. The remaining four become 4 / 2 = 2 lone pairs. The lone pairs repel the O-H bonds. By convention, they are placed on top of the two H atoms.
Similarly, atoms in a SO₂ molecule demands an extra 2 × 2 + 2 = 6 electrons for its three atoms to become chemically stable. It would form 6 / 2 = 3 chemical bonds. Loops are unlikely in molecules without carbon. As a result, one of the two O atoms would form two bonds with the S atom while the other form only one.
Atoms are unstable with an odd number of valence electrons. The S atom in SO₂ would have become unstable if it contribute one electron to each of the three bond. It would end up with 3 × 2 + 3 = 9 valence electrons. One possible solution is that it contributes two electrons in one particular bond. One of the three bonds would be a coordinate covalent bond, with both electrons in that bond from the S atom. In some textbooks this type of bonds are also known as dative bonds.
Dots and crosses denotes the origin of electrons in a bond. Use the same symbol for electrons from the same atom. Electrons from the oxygen atoms O are shown in blue in the sketch. They don't have to be colored.
The question is incomplete, here is the complete question:
Classify each element. Note that another term for main group is representative, another term for semi-metal is metalloid, and the inner transition metals are also called the lanthanide and actinide series.
Hf, Am, In, Ta, As, Se, Rn
<u>Answer:</u>
Hafnium and tantalum are transition elements.
Americium is a inner transition element.
Indium, Selenium and Radon are main group elements.
Arsenic is a metalloid.
<u>Explanation:</u>
Main group elements are the elements which belong to s block and p block. They are also known as representative elements.
S-block elements are defined as the elements whose last electron enters s-sub shell. The general electronic configuration of these elements is
P-block elements are defined as the elements whose last electron enters p-sub shell. The general electronic configuration of these elements is
Metalloids are defined as the elements which show intermediate properties between metals and non-metals. There are 7 metalloids in the periodic table. They are: Boron, Silicon, germanium, Arsenic, Antimony, Tellurium and Polonium.
Transition elements are known as d-block elements. D block elements are defined as the elements whose last electron enters d sub shell. The general electronic configuration of these elements is
Inner transition elements are known as (f block) elements. (F block) elements are defined as the elements whose last electron enters (f subshell). The general electronic configuration of these elements is . They are also known as lanthanide and actinide series.
For the given elements:
- <u>Option 1:</u> Hf
Hafnium is the 72nd element of the periodic table having electronic configuration of
As, the last electron is entering the d subshell, it is a transition element.
- <u>Option 2:</u> Am
Americium is the 95th element of the periodic table having electronic configuration of
As, the last electron is entering the (f subshell), it is a inner transition element.
- <u>Option 3:</u> In
Indium is the 49th element of the periodic table having electronic configuration of
As, the last electron is entering the p subshell, it is a main group element.
- <u>Option 4:</u> Ta
Tantalum is the 73rd element of the periodic table having electronic configuration of
As, the last electron is entering the d subshell, it is a transition element.
- <u>Option 5:</u> As
Arsenic is the 33rd element of the periodic table having electronic configuration of
As, the last electron is entering the p subshell, it is a main group element. It shows an intermediate property of metal and non-metal. Thus, it is a metalloid.
- <u>Option 6:</u> Se
Selenium is the 34th element of the periodic table having electronic configuration of
As, the last electron is entering the p subshell, it is a main group element.
- <u>Option 7:</u> Rn
Radon is the 86th element of the periodic table having electronic configuration of
As, the last electron is entering the p subshell, it is a main group element.