Which of these is an isoelectronic series? 1) na+, k+, rb+, cs+ 2) k+, ca2+, or, s2– 3) na+, mg2+, s2–, cl– 4) li, be, b, c 5) n
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An isoelectronic series is where all of the ions listed have the same number of electrons in their atoms. When an atom has net charge of zero or neutral, it has equal number of protons and electrons. Hence, it means that the atomic number = no. of protons = no. of electrons. If these atoms become ions, they gain a net charge of + or -. Positive ions are cations. This means that they readily GIVE UP electrons, whereas negative ions (anions) readily ACCEPT electrons. So, to know which of these are isoelectronic, let's establish first the number of electron in a neutral atom from the periodic table:
Na=11; K=19; Rb=37; Cs = 55; Ca=20; S=16; Mg=12; Li=3; Be=4; B=5; C=6
A. Na⁺: 11-1 = 10 electrons
K⁺: 19 - 1 = 18 electrons
Rb⁺: 37-1 = 36 electrons
B. K⁺: 19 - 1 = 18 electrons
Ca²⁺: 20 - 2 = 18 electrons
S²⁻: 16 +2 = 18 electrons
C. Na⁺: 11-1 = 10 electrons
Mg²⁺: 12 - 2 = 10 electrons
S²⁻: 16 +2 = 18 electrons
D. Li=3 electrons
Be=4 electrons
B=5 electrons
C=6 electrons
The answer is letter B.
The answer is predict, because it fits, and because someone can predict the outcome of something.
Answer:
frogs, fish and aquatic (water-dwelling) insects
Explanation:
Answer:The compound created by calcium and chlorine is calcium chloride, and the formula for this compound is CaCl2 .
Explanation:
Answer:
The mass percent of Al(OH)₃ is 15.3%
Explanation:
The reaction is:
Al(OH)₃ + 3HCl = AlCl₃ + 3H₂O
The excess acid is neutralized with a solution of sodium hidroxide, in the reaction:
NaOH + HCl = NaCl + H₂O
The total moles of HCl is:
From the second titration, the moles of excess of HCl is:
The difference between the total and excess of HCl, it can be know the moles that reacts with the aluminum hydroxide, is:
The ratio between HCl and Al(OH)₃ is 3:1. The MW for aluminum hydroxide is 78 g/mol, thus:
The percentage of Al(OH)₃ is:
%
