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, Ar = 18
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
Ar: 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.
Your answer would be C. Alpha decay involves the ejection of 2 protons and 2 neutrons from the nucleus for a total of 4 amu lost. This form of decay is most common in heavy elements.
Answer:
1.840 x 10⁻³ mol HBrO₃
Explanation:
To find the moles of bromic acid (HBrO₃), you should (1) convert milligrams to grams (by dividing by 1,000) and then (2) convert moles to grams (via molar mass from periodic table).
Molar Mass (HBrO₃): 1.008 g/mol + 79.904 g/mol + 3(15.998 g/mol)
Molar Mass (HBrO₃): 128.906 g/mol
2.372 x 10² mg HBrO₃ 1 g 1 mole
---------------------------------x----------------x------------------ = 1.840 x 10⁻³ mol HBrO₃
1,000 mg 128.906 g
