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mars1129 [50]
3 years ago
7

Write the empirical formula for at least four ionic compounds ca2+.v5+,f-,s2

Chemistry
1 answer:
Vesna [10]3 years ago
8 0
Using these Elements. Here would be the 4 ionic compounds.

CaF2
VF5
CaS
V2S5
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You discover a new substance that mixes well with H2O initially, but eventually the particles sink to the bottom. What is the BE
AVprozaik [17]
I believe this would be colloid
7 0
3 years ago
On what is the geologic time scale based?
nekit [7.7K]

Answer: Either A or D

Geologists and paleontologists constructed the geologic table based on the relative positions of different strata and fossils, and estimated the time scales based on studying rates of various kinds of weathering, erosion, sedimentation, and lithification.

5 0
3 years ago
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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:<em> It would have smaller atomic radii than Si and higher ionization energies than Si.</em>

Explanation:

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

Since, the inner electrons repel the outer electrons, t<em>he effective nuclear charg</em>e 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, <em>the effective nuclear charge (Zeff)</em> 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 <em>higher electronegativity than silicon (Si)</em><em>.</em>

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 <em>atomic radii and the ionization energy</em>.

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
2 years ago
Give two examples of diffusion process in plants and animals.
lisabon 2012 [21]

answer:

in plants

Transport manufactured food from the leaves to others parts of the plant

Facilitates gaseous exchange through the stomata in the leaves to other parts of the plant

in animal

Exchange of respiratory gases across respiratory services

Excretion of nitrogenous waste in some unicellular organisms

Explanation:

Hope it benefit

3 0
2 years ago
Which of the following has a polar covalent bond? b. Which of the following has a bond closest to the ionic end of the bond spec
Marizza181 [45]

Explanation:

<u>Polar covalent bonding is the type of the chemical bond in which the pair of the electrons is unequally shared between the two atoms.</u> As a result, the atom with higher value of electronegativity acquires a slightly negative charge and the atom with lower value of electronegativity acquires a slightly positive charge.

In the molecule of CH_3NH_2, the bond which is closest to ionic end of bond spectrum is <u>N-H bond</u> because the nitrogen atom is more electronegative than hydrogen and is ionic in nature.

In the molecule of CH_3CH_3, the bond which is closest to ionic end of bond spectrum is <u>no one</u> because there is not much difference between carbon and hydrogen for the bond to be said as ionic.

In the molecule of CH_3OH, the bond which is closest to ionic end of bond spectrum is <u>O-H bond</u> because the oxygen atom is more electronegative than hydrogen and is ionic in nature.

5 0
3 years ago
Read 2 more answers
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