Answer:
Name the element: Beryllium
Number of shells: 4
Valence electrons: 2
Explanation:
Answer:
This is isotope of barium
Explanation:
It has atomic number of 56, mass number is 130 (56 + protons + 76 neutrons) oxidation number is +2 it has two more protons than electrons ( 56 - 54 = 2 )
Answer:
-54 kJ/mol
Explanation:
Given that:
A student mixed 50 ml of 1.0 M HCl and 50 ml of 1.0 M NaOH in a coffee cup calorimeter and calculated the molar enthalpy change of the acid-base neutralization reaction to be –54 kJ/mol
i.e
50 ml of 1.0 M HCl + 50 ml of 1.0 M NaOH -----> -54 kJ/mol
If he repeat the same experiment with :
100 ml of 1.0 M HCl + 100 ml of 1.0 M NaOH. ------> ????
From The experiment; the molar enthalpy of change of the acid-base neutralization reaction will be -54 kJ/mol
This is because : The second reaction requires 50 ml in order to neutralize the reaction, then the remaining 50 ml will be excess, Hence, there is no change in the enthalpy of the reaction.
Similarly; we can assume that :
In the first reaction; P moles of is used to liberate Q kJ heat ; then the change in molar enthalpy will be Q/P (kJ/mol).
SO; when he used 100 ml ;
then the amount of moles used is double, likewise the heat liberated will be doubled ;
So;
2P moles is used to liberate 2Q kJ heat ;
2P/2Q = Q/P ( kJ/mol) = -54 kJ/mol
Answer:
Elements with low ionization energies.
Explanation:
The ionization energy of an atom reffers to the amount of energy that is required to remove an electron from the gaseous form of that atom or ion.
The greater the ionization energy, the more difficult it is to remove an electron. The ionization energybis one of the indicator that shows the reactivity of an element. Elements with a low ionization energy such as metals are usually reffered to as a reducing agents and form cations, this give metals the tendency to
give away their valence electrons when bonding, whereas non-metals tend to take electrons.
Metallic elements have different properties such as shiny, heat and electricity conductivity . They are malleable and ductile Some metals, such as sodium, are soft and can be cut with a knife. while some are very hard such as iron.
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