Answer:
0.196 M
Explanation:
First, we have to calculate the moles of sodium hydroxide.
moles = mass / molar mass
moles = 3.9280 g / (39.997 g/mol) = 0.098207 mol
It is important to realize that even though 300 mL is the volume of water firstly added to dissolve the hydroxide, the flask is then filled to the mark, meaning that the volume of the solution is 500 mL = 0.500 L.
The molar concentration of sodium hydroxide is:
The concentration is an intensive property, that is, it does not depend on the amount of matter. As a consequence, the concentration of the 50 mL of solution in the buret is the same as the concentration in the flask.
To determine what elements are represented by the electron configuration given above, we need to know the sum of the exponents of each term or subshell involved in the configuration as this represent the atomic number of the element.
Atomic Number Element
<span>1s2 2s2 2p6: 2 + 2 + 6 = 10 neon
1s2 2s2 2p6 3s2 3p3: </span>2 + 2 + 6 + 2 + 3 = <span>15 phosphorus
1s2 2s2 2p6 3s2 3p6 4s1: </span>2 + 2 + 6 + 2 + 6+1 = <span>19 potassium
1s2 2s2 2p6 3s2 3p6 4s2 3d8: 20 + 8 = 28 nickel
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d3: 30 + 6 + 2 +3 = 41 niobium</span>
If you are asking which is the most abundant, Uranium-238 is
Answer:
Representative Elements
Explanation:
Representative elements are chemical elements of the long groups of the periodic table identified by the letter A, headed by the elements hydrogen, beryllium, boron, carbon, nitrogen, oxygen, fluorine and helium, as they appear in the periodic table of the elements. .
They are characterized by presenting "external" electronic configurations in their fundamental state ranging from ns1 to ns2np6, unlike the transition elements and internal transition elements.
The representative elements are the elements of groups 1 and 2 (block s), and of groups 13 to 18 (block p) .2 Until a few years ago, these groups were identified with Roman numerals from I to VII with the letter A.3 The elements of group 12 are generally considered as transition metals, however, zinc (Zn), cadmium (Cd), and mercury (Hg) share some properties of both groups, and some scientists believe they should be included as representative elements or elements of the main groups.
Representative elements (with some of the lighter transition metals) are the most abundant elements on earth, in the solar system, and in the universe.
The representative elements are divided into eight groups and are characterized in that their electronic distribution ends in s-p or p-s. The group number results from adding the electrons in the sub-levels s or s and p of the last level.
Answer:
Nope, not a chemical change.
Explanation:
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