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JulsSmile [24]
3 years ago
8

Help Me Please

Chemistry
2 answers:
GaryK [48]3 years ago
6 0

in the periodic table, elements are classified in the ascending order of their atomic numbers. atomic number is the number of protons

in elements the number of protons is equal to the number of electrons

the condensed notation of electron configuration is when the symbol of the noble gas closest to the elements electron configuration is mentioned.

[He] 2s² - number of electrons in He is 2 , and 2 more electrons in the s subshell adds upto a sum of 4 electrons. number of protons = number of electrons

then number of protons = 4

then atomic number is 4. element with atomic number 4 is Be

the element is Be


[Ne] 3s² 3p⁵

Ne atomic number is 10. 10 + 7 electrons in the third shell = 17 electrons in total

atomic number - 17 is Cl

element is Cl


[Xe] 6s¹

Xe atomic number is 54, 54 + 1 electron in the sixth shell = 55 electrons in total

atomic number of 55 is Cs

element is Cs


[Ar] 4s² 3d⁹

Ar atomic number is 18. 18 + 2 electrons in 4th shell and 9 in d subshell of 3rd shell = 29 electrons in total

atomic number of 29 is Cu

element is Cu

Shtirlitz [24]3 years ago
6 0
[He]2s2: Be
[Ne]3s23p5: Cl
[Xe]6s1: Cs
<span> [Ar]4s23d9: Cu</span>
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Convert 8.876 × 10^12 m^2 to units of km^2.
Darya [45]

Answer:

8.876\times 10^{18}\ km^2

Explanation:

In this problem, we need to convert 8.876 \times 10^{12}\ m^2 to km².

We know that,

1 km = 1000 m

⇒ 1 km² = 10⁶ m²

So,

8.876 \times 10^{12}\ m^2=8.876 \times 10^{12}\times 10^6\ km^2\\\\=8.876\times 10^{18}\ km^2

So, 8.876 \times 10^{12}\ m^2 is equal to 8.876\times 10^{18}\ km^2.

7 0
3 years ago
What is the percent composition HCN?
kupik [55]

Answer:

see calculations in explanation

Explanation:

percent = part/total x 100%

part = ∑ atomic mass of element

  • hydrogen = 1.008 amu (atomic mass units)
  • carbon = 12.011 amu
  • nitrogen = 14.007 amu

total = ∑ molecular mass of compound

       = H amu  +  C amu +  Namu

       = 1.008 amu + 12.011 amu + 14.007 amu

       = 27.026 amu

%H = (1.008amu/27.026amu)100% = 3.730%

%C = (12.011amu/27.026amu)100% = 44.442%

%N = (14.007amu/27.026amu)100% = 51.827%

Check results ∑%values = 100%

3.730% + 44.442% + 51.827% = 99.999% ≅ 100%

7 0
3 years ago
Which is true about the potential energy of the reactants in this reaction pathway
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it is equal to the potential energy of the products

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What type of reaction is shown below? <br> Ca + 2H2O - Ca(OH)2 + H2
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The element Ca accepts OH- and H2O loses the same group to form new element H2
So the correct answer is
Single replacement also known as single displacement.
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