For the second one it is physical
Period 4 transition element that forms 2+ ion with a half‐filled d sub level is
Manganese (Mn)
What is the half-filled d sub-level?
Transition metals are an interesting and challenging group of elements. They have perplexing patterns of electron distribution that don’t always follow the electron-filling rules. Predicting how they will form ions is also not always obvious.
Transition metals belong to the d block, meaning that the d sublevel of electrons is in the process of being filled with up to ten electrons. Many transition metals cannot lose enough electrons to attain a noble-gas electron configuration. In addition, the majority of transition metals are capable of adopting ions with different charges. Iron, which forms either the Fe2+ or Fe3+ ions, loses electrons as shown below.
Some transition metals that have relatively few d electrons may attain a noble-gas electron configuration. Scandium is an example. Others may attain configurations with a full d sublevel, such as zinc and copper.
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Answer:
beryllium: 2 valence electrons
nitrogen: 5 valence electrons
oxygen: 6 valence electrons
fluorine: 7 valence electrons
magnesium: 2+ valence electrons
phosphorus: 5 valence electrons
sulfur: 6 valence electrons
chlorine: 7 valence electrons
Explanation:
Answer:
five half lives
Explanation:
Half-life is the time required for a quantity to reduce to half of its initial value.
How many half lives it would take to reach 3.13% form 100% of it's initial concentration:
100% - 50% : First Half life
50% - 25%: Second Half life
25% - 12.5%: Third Half life
12.5% - 6.25%: Fourth Half life
6.25% - 3.125%: Fifth Half life
This means it would take five half lives to get to 3.125% (≈ 3.13%) of it's original concentration.
