_____ C8H8 + _____ O2 _____ CO2 + ____

Suppose a laboratory wants to identify an unknown pure substance. The valence electrons of the substance's atoms feel an effecti

zalisa [80]

Answer:

The answer is the third option in the list: It would have smaller atomic radii than Si and higher ionization energies than Si.

Explanation:

The effective nuclear charge is that portion of the total nuclear charge that a given electron in an atom feels.

Since, the inner electrons repel the outer electrons, the effective nuclear charge of a determined electron is the sum of the positive charge (number of protons or atomic number) that it feels from the nucleus less the number of electrons that are in the shells that are are closer to the nucleus than the own shell of such (determined) electron.

Mathematically, the effective nuclear charge (Zeff) is equal to the atomic number (Z) minus the amount (S) that other electrons in the atom shield the given (determined) atom from the nucleus.

Zeff = Z - S.

Since, the valence electrons are the electrons in the outermost shell of the atom, you can find certain trend for the value Zeff.

Let's look at the group to which Si belongs, which is the group 14. This table summarizes the relevant data:

Element Z Group # valence electrons S Zeff = Z - S

C 6 14 4 6 - 4 = 2 6 - 2 = +4

Si 14 14 4 14 - 4 = 10 14 - 10 = +4

Ge 32 14 4 32 - 4 = 28 32 -28 = +4

Sn 50 14 4 50 - 4 = 46 50 - 46 = +4

Pb 82 14 4 82 - 4 = 78 82 - 78 = +4

With that, you have shown that the valence electrons of the unknown substance's atoms feel an effective nuclear charge of +4 and you have a short list of 4 elements which can be the unknown element: C, Ge, Sn or Pb.

The second known characteristic of the unknown substance's atoms is that it has a higher electronegativity than silicon (Si).

So, you must use the known trend of the electronegativity in a group of the periodic table: the electronegativity decreases as you go down in a group. So, three of the elements (Ge, Sn, and Pb) have lower electronegativity than Si, which has left us with only one possibility: the element C. The valence electrons of carbon (C) atoms feel an effective nuclear charge of +4 and it carbon has a higher electronegativity than silicon.

Other two periodic trends attending the group number are the atomic radii and the ionization energy.

The atomic radii generally increases as you go from top to bottom in a group. This is because you are adding electrons to new higher main energy levels. So, you can conclude that the originally unknwon substance (carbon) has a smaller atomic radii, than Si.

The ionization energies generally decreases as you go from top to bottom in a group. This os due to the shielding effect: as seen, the effective nuclear charge of the atom's valence electrons remains constant, while the distance of the electrons from the nucleus increases (the valence electrons are farther away from the nucleus), which means the upper the element in a given group, the larger the ionization energy of the atoms.

With this, our conclusions about the unnkown substance are:

Since it has a higher electronegativity value than silicon (Si), it is right up of Si, and there is on only element possible element than can be (C).

Since, it is upper than silicon (Si), it would have smaller atomic radii.

Due to the shielding effect, it would have larger ionization energies.

The answer is the third option in the list: It would have smaller atomic radii than Si and higher ionization energies than Si.

6 0

3 years ago

In the following reactions identify which substances are solid (s) or aqueous (aq). 1. Li,SO4( aq ) + MgCl, ( aq ) - 2LICI ( 2LI

IrinaK [193]

Answer:

Ok

Explanation:

4 0

3 years ago

Why is using only clean glassware important?

stealth61 [152]

Good laboratory technique demands clean glassware because the most carefully executed piece of work may give an erroneous result if dirty glassware is used. In all instances, glassware must be physically and chemically clean and in many cases, it must be bacteriologic-ally clean or sterile.

6 0

3 years ago

Read 2 more answers

A hydrogen atom requires a minimum energy of 2.18×10^-18 J atom to remove an electron from its ground state level. Determine whe

frosja888 [35]

Just find the energy of the blueviolet light with a wavelength of 434.0 nm using the formula:

E = hc / lambda

E = energy
c= speed of light = 3 x 10^8 m/s
h = planck's constant = 6.6 x 10^{-34} m^2 kg / s
lambda = 434 nm = 434 x 10^{-9} m

Putting these values (with appropriate units) in the above formula :

we get: Energy, E = 4.5 x 10^{-19} J

E = 0.45 x 10^{-18} J

Now, the minimum energy is 2.18×10^-{18} J but our energy is 0.45 x 10^{-18} J which is less.
Means the electron will not be removed

5 0

3 years ago

CaCO3 For each of the following compounds, decide whether the compound's solubility in aqueous solution changes with pH. If the

Slav-nsk [51]

Answer:

Hello attached below is the data found in Aleks Data tab

answer :

i) N0

ii) N0

iii) YES , pH of highest solubility = 5

Explanation:

i) For CuBr

solubility does not change with pH hence answer = NO

ii) For MgCl2

solubility does not change with pH hence the answer = NO

iii) For Ba(OH) 2

Solubility does change with pH hence the answer = YES

and the pH at which the highest solubility will occur is = 5

attached below is the reason for the answers given

4 0

3 years ago

_____ C8H8 + _____ O2 _____ CO2 + _____ H2O

___ C8H8 + _ O2 _ CO2 + ___ H2O