Your Question: There are two kinds of elements that didn't appear on the periodic table until after 1892. What kinds are they and why do you think it took so long to discover them?
The Answer: Moseley’s analysis enabled chemists to refine the table further and reveal more gaps, which suggested that there were more new elements waiting to be discovered, with atomic numbers 43, 61, 72 and 75. Scientists subsequently found these elements—now known as technetium, promethium, hafnium and rhenium, respectively.
Explanation: Physicist Henry Moseley discovered the atomic number of each element using x-rays, which led to more accurate organization of the periodic table. We will cover his life and discovery of the relationship between atomic number and x-ray frequency, known as Moseley's Law.
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Answer:
74.09 atm
Explanation:
Using the gas laws ( Charles and Boyle's law). We have the formula ,
P1/T1 = P2/T2
Where P1 = 30.3atm
T1 = -100 degree Celsius
to kelvin = -100+ 273 = 173K
T2 = 150 degree Celsius
To Kelvin = 150 = 150+273 = 423K
Imputing values
P1/T1 = P2/T2
30.3/173 = P2/ 423
Cross multiply
173×P2 = 30.3 ×423
173P2 = 12816.9
Divide both sides by 173
P2 = 12816.9/173
P2 = 74.09 atm
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<span>1,3-cylohexadiene i synthesized starting from cyclohexane in following 4 steps.
1) Free Radical Substitution Rxn: Halogenation of cyclohexane in the presence of UV yield chlorocyclohexane.
2) Elimination Rxn: Dehydrohalogenation of chlorocyclohexane yields cyclohexene.
3) Halogenation of Cyclohexene (
Electrophillic Addition Rxn) gives 1,2-dihalocyclohexane.
4) Elemination Rxn: When dibromocyclohexane is treated with KOH and heated it gives 1,3-cyclohexadiene as shown below,</span>
Answer:
1)
(500.mL)(.200M)/.150M = 667 mL
667mL - 500mL = 167mL of water is needed
2)
1.0 L = 1000mL
M1 V1 = M2 V2
(1.6 mol/L) (175 mL) = (x)(1000mL)
x = .28M
Answer:
El Big Bang fue el momento, hace 13.800 millones de años, cuando el universo comenzó como una pequeña y densa bola de fuego que explotó. La mayoría de los astrónomos utilizan la teoría del Big Bang para explicar cómo comenzó el universo.
Explanation:
