The correct answer is higher melting point, bound by metal metal bonds.
While alkali metals only have one valence electron, alkaline earth metals have two. Metal to metal connections hold the metals together. Alkaline earth metals have a stronger metallic connection and a higher melting point because they have two valence electrons.
the characteristics that Group 2 metals excel in over Group 1 metals.
- Initial Ionization Potential
- Group 2 items are more difficult than group 1 elements.
- Strong propensity to produce bivalent compounds
As a result, group 2 metals have stronger metallic bonding, which leads to increased cohesive energy and compact atom packing. This explains why group 2 metals are harder and have higher melting and boiling temperatures than group 1 metals.
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Answer:
True water is wet because when something is wet in this case it's water it has water on it at a molecular level. Water molecules are bonded on top of each other so it's wet.
Answer:
weak bonds break and strong bonds form
Explanation:
An exothermic reaction is a chemical reaction in which heat energy is evolved during the reaction process.
Bond formation requires energy while bond breakage releases energy. More energy is needed for the formation of weak bonds as compared to strong bonds.
<em>Hence, when weak bonds break, they release more energy than needed to make a corresponding strong bond leading to the release of the remaining energy as heat.</em>
The number of moles of gas lost is 0.0213 mol. It can be solved with the help of Ideal gas law.
<h3>What is Ideal law ?</h3>
According to this law, "the volume of a given amount of gas is directly proportional to the number on moles of gas, directly proportional to the temperature and inversely proportional to the pressure. i.e.
PV = nRT.
Where,
- p = pressure
- V = volume (1.75 L = 1.75 x 10⁻³ m³)
- T = absolute temperature
- n = number of moles
- R = gas constant, 8.314 J*(mol-K)
Therefore, the number of moles is
n = PV / RT
State 1 :
- T₁ = (25⁰ C = 25+273 = 298 K)
- p₁ = 225 kPa = 225 x 10³ N/m²
State 2 :
- T₂ = 10 C = 283 K
- p₂ = 185 kPa = 185 x 10³ N/m²
The loss in moles of gas from state 1 to state 2 is
Δn = V/R (P₁/T₁ - P₂/T₂ )
V/R = (1.75 x 10⁻³ m³)/(8.314 (N-m)/(mol-K) = 2.1049 x 10⁻⁴ (mol-m²-K)/N
p₁/T₁ = (225 x 10³)/298 = 755.0336 N/(m²-K)
p₂/T₂ = (185 x 10³)/283 = 653.7102 N/(m²-K)
Therefore,
Δn = (2.1049 x 10⁻⁴ (mol-m²-K)/N)*(755.0336 - 653.7102 N/(m²-K))
= 0.0213 mol
Hence, The number of moles of gas lost is 0.0213 mol.
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Answer:
A. there is an isotope of lanthanum with an atomic mass of 138.9
Explanation:
By knowing the different atomic masses of both Lanthanum atoms, we can not tell anything about their occurence in nature. Therefore, all the last three options are incorrect. Because, the atomic mass does not tell anything about the availability or natural abundance of an element.
Now, the isotopes of an element are those elements, which have same number of electrons and protons as the original element, but different number of neutrons. Therefore, they have same atomic number but, different atomic weight or atomic masses.
Hence, by looking at an elements having same atomic number, but different atomic masses, we can identify them as isotopes.
Thus, the correct option is:
<u>A. there is an isotope of lanthanum with an atomic mass of 138.9.</u>
