# Tag Info

1

Three oxygen atoms do form a molecule (look up "ozone").

1

Chemical bonds occur because of the outer electron shell also known as a valence electron shell. Oxygen has six electrons and it's valence shell. An atom wants 8 electrons in its valence shell. They both decide to share two electrons. That way they both have full valence shells. NaCl works because Cl wants 1 more electron and Na wants to get 7 more. Mg needs ...

0

Correlation energy is generally defined as the difference between the true total energy and the Hartree-Fock limit. There are mainly two reasons for HF not being exact. Firstly, it approximates the many-body wavefunction as a single Slater determinant, while the exact result must be taken as a combination of many Slater determinants. This leads to a ...

1

It's thirty-five (!) years since I last did an HF/SCF calculation, but in those days our code worked by minimising the energy: $$E_{HF} = \langle \Psi_{HF} | H | \Psi_{HF} \rangle$$ where $\Psi_{HF}$ is the approximate wavefunction expressed as a sum of some convenient basis set of functions. Once you'd done the HF/SCF calculation you'd do a CI ...

-1

About this issue you can not finally conclude that its oxidation stage is 6,2 ,1 and -2 because the rules governing it has not been found. Rather you are to say the oxidation number of any element in a periodic table is found based on the column of the group it falls in to.

3

The expansion upon freezing comes from the fact that water crystallizes into an open hexagonal form. This hexagonal lattice contains more space than the liquid state.

0

Wood can only be solid because it's a very specific arrangement of atoms. If you liquified or vaporized all the elements in it, they wouldn't be wood. You also can't have liquid crystals, unless you count liquid crystals. Or a liquid computer.

1

$$\newcommand{\ket}[1]{| #1 \rangle}$$ I'll try to answer the last two. with an arbitrary superposition, the probability density for the electron could be anything - can we actually find the coefficients of the superposition an electron actually is in? I'm a little confused about what you mean here. If we are given $\ket{\psi}$ as a combination of, ...

2

Regarding your first two points: The symmetry axis of an orbital is free for a free atom. If it's bound to some other atom through one of these one-dimensionally elongated orbitals, the orientation of one orbital is fixed. If you take e.g. carbon, silicon or germanium, you have one s orbital and three p orbitals, which are oriented perpendicular to each ...

5

Most substances can perform a large number of phase transitions. There are even different kinds of phase transitions and sometimes two phases can be connected by more than one process. The quantities governing what phase transition occurs are so-called state variables; temperature and pressure are the best known representatives, but e.g. magnetic fields can ...

2

When a substance skips the liquid phase and deposits as a solid directly from its gas phase, it's called deposition. When it evaporates directly from solid to gas it's called sublimation. The key to this happening is the equilibrium vapor pressure of the substance, which is the pressure exerted by its gas phase when it's in thermodynamic equilibrium with ...

1

This is more chemistry than physics... The color of a material is due to an interaction of the light with chemical bonds (usually double bonds) in the dye. The UV component of sunlight tends to knock electrons out of double bonds and can in time cause changes to the chemical composition which we experience as bleaching. For a more thorough and ...

Top 50 recent answers are included