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tankabanditka [31]
2 years ago
8

How to tell how many valence electrons an atom has?

Chemistry
1 answer:
lbvjy [14]2 years ago
6 0

Answer:  Count only the electrons in the highest shell s and p orbitals when determining valence.

Explanation:  I'm glad you asked this question.  It is often not well explained.   The term valence electrons is assigned to only the electrons in an element's highest energy level.  These reside only in the s and p orbitals, and not the d or f, as I'll explain later.  The s orbital can hold 2 electrons and the p can hold 6.  Potassium, K, has an s orbital in its highest energy shell, 4.  It contains only 1 electron, so it has a valency of 1.  

Calcium, Ca, has 2 in its highest energy level: 4s^2, so it has a valency of 2.   Moving to the right, the element scandium, Sc, add another electron, but it goes into the 3d orbital.  3d is in the 3rd energy shell, so it is not counted as a valence electron.  Only after we move further right, to gallium, Ga, do we start adding electrons to the 4th energy level again - the 4p orbitals can accept up to 6 electrons.  Ga has 3 valence electrons - 2 in the 4s and 1 in the 4p.  Oxygen has 2 in the 2s and 4 in the 4p orbitals, for a total of 6.  It is close to having a comple outer shell (2 in the 2s and 6 in the 2p).  Just 2 more electrons would fill both the 2s and 2p orbitals for a total of 8 valence electrons, a stable configuration (the same configuration as thje stable gas Neon).

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How is the melting point of a substance recorded
GrogVix [38]

1. slowly heat stubstance.

2. once the substance is at the most liqued state take the temp. that's the melting point of that subtance.

hope that helps, any other questions feel free to DM me dont wate your points. :)

6 0
3 years ago
How many moles of water were lost if the amount of water lost was 0.456 grams? Do not include units and assume three significant
nika2105 [10]
<h3>Answer:</h3>

0.0253 mol H₂O

<h3>General Formulas and Concepts:</h3>

<u>Math</u>

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

  1. Brackets
  2. Parenthesis
  3. Exponents
  4. Multiplication
  5. Division
  6. Addition
  7. Subtraction
  • Left to Right<u> </u>

<u>Chemistry</u>

<u>Atomic Structure</u>

  • Reading a Periodic Table

<u>Stoichiometry</u>

  • Using Dimensional Analysis
<h3>Explanation:</h3>

<u>Step 1: Define</u>

[Given] 0.456 g H₂O (water)

<u>Step 2: Identify Conversions</u>

[PT] Molar Mass of H - 1.01 g/mol

[PT] Molar Mass of O - 16.00 g/mol

Molar Mass of H₂O - 2(1.01) + 16.00 = 18.02 g/mol

<u>Step 3: Convert</u>

  1. [DA] Set up:                                                                                                     \displaystyle 0.456 \ g \ H_2O(\frac{1 \ mol \ H_2O}{18.02 \ g \ H_2O})
  2. [DA] Multiply/Divide [Cancel out units]:                                                          \displaystyle 0.025305 \ mol \ H_2O

<u>Step 4: Check</u>

<em>Follow sig fig rules and round. We are given 3 sig figs.</em>

0.025305 mol H₂O ≈ 0.0253 mol H₂O

3 0
2 years ago
1(a). What is the solubility of calcium chloride (CaCl2) at 5°C?
In-s [12.5K]

Answer:

60 g/100 g water  

Explanation:

Find 5 °C on the horizontal axis.

Draw a line vertically from that point until you reach the solubility curve for CaCl₂.  

Then draw a horizontal line from there to the vertical axis.

The solubility of CaCl₂ is 60 g/100 g water.

7 0
3 years ago
harry potter flips a coin (not magical ) 8 times. He gets heads 1 time. What are the odds that his next flip will be heads? A 10
rodikova [14]
C. 50%
Unless the question is saying he only gets heads once, in which case it would be 0%. Or the coin could have 2 heads. Then it would be 100%.
But I'm pretty sure it's 50%.
7 0
3 years ago
Write the formulas of the three singly chlorinated isomers formed when 2,2-dimethylbutane reacts with Cl2 in the presence of lig
Tems11 [23]

The molecule with same molecular formula but different arrangement of atoms is said to be an isomer.

When 2,2-dimethylbutane reacts with chlorine in the presence of light gives three isomers that is CH_{3}C(CH_{3})_{2}CHClCH_{3} (3-chloro-2,2-dimethylbutane), ClCH_{2}C(CH_{3})_{2}CH_{2}CH_{3} (1-chloro-2,2-dimethylbutane) and ClCH_{2}CH_{2}C(CH_{3})_{2}CH_{3} (1-chloro-3,3-dimethylbutane).

In above case, the molecular formula of all isomers are same i.e.C_{6}H_{13}Cl but chlorine is arranged in different positions of carbon. Thus, results isomers.

The reaction is shown in the image.


3 0
3 years ago
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