What is the number of electrons and protons can be seen in this atom?

A student uses 5g of carbon to extract copper metal from its ore:

Umnica [9.8K]

Answer:

drt4gxhknwo

Explanation:

4 0

2 years ago

Describe 5 importance matter to undergo changes

Rzqust [24]

Answer:

melting, freezing, sublimation, deposition, condensation, and vaporization. These changes

Explanation:

hope it helps...i dont know if its right but i hope it helps

3 0

3 years ago

Which statement about AHf is true?

Pachacha [2.7K]

Answer:

It is positive when the bonds of the product store more energy than those of the reactants.

Explanation:

The standard enthalpy of formation, ΔHf, is defined as the energy required to form 1 mole of a substance from its contituent elements under standard conditions of pressure and temperature.

Then, per defintion, when the elements are already at their standard states, there is not energy involved to form them from that very state; this is, the standard enthalpy of formation of the elements in their standard states is zero.

It is not zero for the compounds in its standard state, because energy should be released or absorbed to form the compounds from their consituent elements. Thus, the first choice is false.

When the bonds of the products store more energy than the those of the reactants, the difference is:

ΔHf = ΔHf products - ΔHf reactants > 0, meaning that ΔHf is positive. Hence, the second statement is true.

Third is false because forming the compounds may require to use (absorb) or release (produce) energy, which means that ΔHf could be positive or negative.

Fourth statement is false, because the standard state of many elements is not liquid. For example, it is required to supply energy to iron to make it liquid. Thus, the enthalpy of formation of iron in liquid state is not zero.

3 0

3 years ago

Arrange the elements in decreasing order of first ionization energy.

just olya [345]

Answer:

The decreasing order of first ionization energy: Se > Ge > In > Cs

The decreasing order of first ionization energy: x > y > z

Explanation:

Ionization energy refers to the energy needed to completely pull out an electron from the valence shell of a neutral gaseous atom.

First ionization energy is the energy involved in the removal of first valence electron.

In the periodic table, down the group, as atomic radius of elements increases, the ionization energy decreases

Whereas, across a period, as atomic radius of elements decreases, the ionization energy increases.

PART (A):

Position of the given elements in the periodic table:

Indium (In): Group 13, period 5

Germanium (Ge): Group 14, period 4

Selenium (Se): Group 16, period 4

Caesium (Cs): Group 1, period 6

Thus, the increasing order of atomic radius: Se < Ge < In < Cs

Therefore, the decreasing order of first ionization energy: Se > Ge > In > Cs

PART (B):

Given elements:

element x: radius = 110 pm

element y: radius = 199 pm

element z: radius = 257 pm

Thus, the increasing order of atomic radius: x < y < z

Therefore, the decreasing order of first ionization energy: x > y > z

5 0

3 years ago

Complete the hybridization and bonding scheme for xef4.

Vikentia [17]

Xe = VIII = 8 valence electrons
F = VII = 4 (7 ve) = 28 valence electrons

total ve = 8 + 28 = 36 ve

36 - 4(2) = 28 ve
(there are 2 electrons in each bond x 4 bonds)

28 - 4(6) = 4
(We assign the remaining electrons to F atoms)

4 - 2(2) = 0
(Therefore 4 electrons left => we have 2 lone pairs)

The steric number = No. of σ bonds + #lone pairs

= 4 σ bonds + 2 lone pairs = 6 => d²sp³ (6 hybrid orbitals)

4 bonds + 2 lone pairs => square planar

6 0

3 years ago