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igomit [66]
3 years ago
12

Directions: Fill in the blanks to complete the idea. 1. Constellations are group of that form pattems in the night sky 2. Ursa M

ajor, Cassiopeia, and Orion are some common 3. Stars are used to tell and time, predict weather, and to serve as birth sign
PASAGOT PO NG MAAYOS
KAILANGAN LANG PO
BRAINLIEST+FOLLOW+HEART+POINT
BAD ANSWER-REPORT
​

Chemistry
1 answer:
siniylev [52]3 years ago
8 0

1. Constellations are group of <u>stars</u> that form pattems in the night sky

2. Ursa Major, Cassiopeia, and Orion are some common <u>constellations</u><u>.</u>

3. Stars are used to tell <u>directions</u> and time, predict weather, and to serve as birth sign.

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An aqueous solution of potassium sulfate is allowed to react with an aqueous solution of calcium nitrate. identify the solid in
Maksim231197 [3]
Ans: Calcium sulfate.

K2SO4 (aq) + Ca(NO3)2 (aq) ⇒ 2KNO3 (aq) + CaSO4 (s)

6 0
3 years ago
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
Which gas will effuse at the rate closest At a particular pressure and temperature, nitrogen gas effuses at the rate of 79mLs. U
Contact [7]

Answer : The rate of effusion of sulfur dioxide gas is 52 mL/s.

Solution :

According to the Graham's law, the rate of effusion of gas is inversely proportional to the square root of the molar mass of gas.

R\propto \sqrt{\frac{1}{M}}

or,

(\frac{R_1}{R_2})=\sqrt{\frac{M_2}{M_1}}       ..........(1)

where,

R_1 = rate of effusion of nitrogen gas = 79mL/s

R_2 = rate of effusion of sulfur dioxide gas = ?

M_1 = molar mass of nitrogen gas  = 28 g/mole

M_2 = molar mass of sulfur dioxide gas = 64 g/mole

Now put all the given values in the above formula 1, we get:

(\frac{79mL/s}{R_2})=\sqrt{\frac{64g/mole}{28g/mole}}

R_2=52mL/s

Therefore, the rate of effusion of sulfur dioxide gas is 52 mL/s.

4 0
3 years ago
Calcium (Ca) and oxygen (O) combine to form an ionic compound. Which best describes the electron dot formula for this compound
Blizzard [7]
CaO because oxygen have 2 dots and calcium as well
(oxygen valency -2
calcium valncy +2)= CaO
3 0
2 years ago
Why is vsepr theory important?
Serga [27]
It is very important<span> to know the shape of a molecule if one is to understand its reactions. It is also desirable to have a simple method to predict the geometries of compounds. For main group compounds, the </span>VSEPR<span> method is such a predictive tool and unsurpassed as a handy predictive method.</span>
7 0
3 years ago
Read 2 more answers
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