The true about element in period or horizontal row of periodic table is
Each element has one more outer electron than the element before it. (answer B)
<u><em> Explanation</em></u>
In periodic table there are four horizontal rows(periods) that is period 1,2,3 and 4.
Across the period each element has one more electron than element before it.
For example Na and Mg which are in periodic 3.
Na has 2.8.1 or [Ne] 3s¹ electron configuration while Mg has 2.8.2 or [Ne] 3S² electron configuration.
Since Mg has 2 outer electrons while Na has 1 outer electron, Mg has more electron than Na.
Answer:
25
Explanation:
25 because when you divide 50/2 it will be 25m/s
A rule of thumb is that elements in the same column or "group" have similar chemical properties. Answer D. has four elements that are all in group 2, or the "alkaline earth metals". The answer is <span>D. 4, 20, 38, 88</span>
Answer:
ΔHrxn = 239 kj/mol
Explanation:
Given data:
Mass of sodium = 0.230 g
Heat produced = 2390 J
Solution:
Chemical equation:
2Na + 2HCl → 2NaCl + H₂
Number of moles of sodium:
Number of moles of sodium = mass / molar mass
Number of moles of sodium = 0.230 g / 23 g/mol
Number of moles of sodium = 0.01 mol
Enthalpy of reaction:
ΔHrxn = 2390 J / 0.01 mol
ΔHrxn = 239000 j/mol
ΔHrxn = 239 kj/mol