Answer:
In none of the reactions ΔH°rxn equal to ΔH°f of the product.
Explanation:
The standard enthalpy of formation (ΔH°f) is the enthalpy change when 1 mole of a product is formed from its constituent elements in the standard states.
1/2 O₂(g) + H₂O(g) ⟶ H₂O₂(g)
ΔH°rxn is NOT equal to ΔH°f of the product because H₂O(g) is not an element but a compound.
Na⁺(g) + F⁻(g) ⟶ NaF(s)
ΔH°rxn is NOT equal to ΔH°f of the product because Na and F are not in their standard states (Na(s); F₂(g)).
K(g) + 1/2 Cl₂(g) ⟶ KCl(s)
ΔH°rxn is NOT equal to ΔH°f of the product because K is not in its standard state (K(s)).
O₂(g) + 2 N₂(g) ⟶ 2 N₂O(g)
ΔH°rxn is NOT equal to ΔH°f of the product because 2 moles of N₂O are formed.
In none of the above ΔHrxn equal to ΔHf of the product.
Elements are ionized because they aspire to be stable. The most stable form are the ones with full octet of electrons, the noble gases which consist of the last column in the periodic table. The rest of the elements either accept or readily donate electrons to conform to the electronic configuration that is the same with the nearest noble gas.
1. Potassium's nearest noble gas is Ar which is one electron fewer. So, when ionized, it donates 1 electron. Hence, K⁺.
2. The nearest noble gas for fluorine is Neon which is 1 electron more. Hence, it has to accept one more electron. Hence, F⁻.
Answer: option C. 2 and 3.
Explanation:
1) Isotopes are atoms of a same element with different number of neutrons. That means that the isotopes of a same element have the same number of protons, since the number of protons is what identify an element.
2) For example, all the atoms of oxygen have 8 protons. But isotope oxygen-16 has 8 neutrons, while oxygen-18 has 10 neutrons.
3) In the figure there are 3 different atoms:
i) atom # 1 has 5 protons and 7 neutrons
ii) atom # 2 has 6 protons and 7 neutrons
iii) atom # 3 has 6 protons and 8 neutrons.
4) Hence the atoms with the same number of protons and different number of neutrons are the #2 and the # 3. So, they are the isotopes of the same element.
According to the octet rule, atoms tend to gain, lose, or share electrons until they are surrounded by__8__ valence electrons.
When an element losses its electron its called a cation. When an element accepted that electron it called anion. This is called an ionic bond.
