chem

What is the difference between an orbital and an orbit?

Orbital is a 3D volume in which there is a probability of finding an electron of a given energy there. an orbit is a 2D path that an electron follows around the nucleus

essential points of the quantum-mechanical model of the atom

- Principle energy levels have sublevels (s, p, d and f) which consist of orbitals - 3 dimensional volumes in which you have a 90% probability of finding an electron - Each orbital can take 2 electrons, and different orbitals have different shapes - s has one spherical orbital, p has 3 two lobed orbitals, d has 5 four lobed orbitals and f has 7 8 lobed orbitals.

essential points of the Bohr model of the atom

- put electrons into Principle Energy Levels (n = 1, 2, 3...) called orbits or shells that existed at specific energies (distances) outside of the nucleus - orbits were specified 2d paths the electron took in orbiting the nucleus Problems - He could not explain the light spectrum of anything but Hydrogen, and Potassium - and elements beyond don't seem to fit into the periodic pattern

What is the order in which sublevels are filled with electrons?

1s2s2p3s3p4s3d4p5s4d5p6s4f5d6p7s5f6d7p

How many electrons can be in one orbital?

2

What are the rules for filling a sublevel that contains more than one orbital (such as the p or d), including number of electrons per orbital and their spin. What is spin?

Aufbrau Principle: always fill the lowest energy level first Hund's Rule: if there is an empty orbital of the same sublevel, put an electron there before pairing any electrons in orbitals Pauli exclusion principle: only electrons with opposite spins can go in the same orbital. Spin is a quality of electrons like the two poles of a magnet- they can have one of two spins - opposite spins complement, like spins cancel

Why is it impossible to describe the motion and position of an electron precisely?

Because electrons are waves and are tiny enough that their position and motion are influenced by the light energy used to visualize them, it makes both their position and motion impossible to measure at the same time accurately.

Describe the Bohr model of the hydrogen atom by showing with a graph or diagram how it accounts for the energy levels of hydrogen

Bohr's model of the H atom includes the Balmer series of visible lines which represent the energies given off when an excited electron falls from a higher energy level to the n=2 energy level.

Where in the periodic table would you find elements with 1 valence electron? What kind of ions do these elements tend to form?

Column 1/Alkali metals, +1 Column 2 = 2 Column 13 = 3 Column 14 - 4 Column 15 - 5 Column 16 - 6 Column 17 - 7 Column 18 - 8

Within the broader EM spectrum, compare the energy of ultraviolet, visible, infrared, and radio waves

From lowest to highest energy - radio, infrared, visible, ultraviolet

What happens inside an atom when it gives off a wavelength of light? Where does the energy come from?

It comes from the conversion of PE into KE as an electron falls to a lower energy level in the atom

What are the distinguishing properties of metals? Of non-metals? Of covalent compounds? Of ionic compounds?

Metals are shiny, malleable, ductile, all but Hg are solid, conduct electricity and heat. Non-metals are brittle, not shiny and can be solid, liquid or gas at room temperature. Covalent compounds are made of two non-metals, have variable melting and boiling points and do not conduct electricity when dissolved in water. Ionic compounds are called salts, are solid at room temperature and conduct electricity when dissolved in water.

In general, atoms are happiest when they can achieve an electron configuration like that of a what?

Noble gas

The wave-mechanical atomic model involves principal energy levels, sublevels, and orbitals. Explain what each of these terms means and how we designate them.

Principle energy levels are the distances outside of the nucleus that the electrons can be. They are designated by n = 1, 2, 3... Sublevels are energy levels within the principle energy levels where pairs of electrons can exists, they are designated by s, p, d and f. Orbitals are the 3D volumes in which those pairs of electrons exist at a given energy.

Within the visible light spectrum, which color has the most energy? Which the least?

Purple has the most, red has the least

What does it mean to say that the energy levels of an atom are quantized/in levels? What is the evidence supporting this statement?

Quantized means energy can only come in multiples of certain numbers, in particular Planck's constant. The evidence supporting this is that when atoms are excited (energy put into them) they only give off certain wavelengths or energies of light, meaning the electrons in them can only move certain distances or energies within the atom.

What are the characteristics of s, p, d, and f sublevels: what is the shape of the orbitals (except f)? How many orbital shapes are there in each kind of sublevel? Which principal energy levels contain which kind of sublevels?

S - spherical, one lobe, lowest energy, holds 2 electrons, starts in n = 1. P - perpendicular, lie on the 3 planes of space, two lobes, next highest energy, hold 6 electrons total in 3 orbital spaces, starts in n=2. D- diagonal, lie in between the 3 planes of space, four lobes, next highest energy, hold 10 electrons in 5 orbital spaces, starts in n=3. F - freaky, 8 lobed, highest energy level, holds 14 electrons in 7 orbital spaces, starts in n=4.

What is the correct pairing of 4 electrons in a p sublevel?

Two electrons paired and two in individual orbitals

What are valence electrons? Why are they important? What sublevels can have valence electrons?

Valence electrons are the electrons in the highest principle energy level in an atom. They are important because they are the electrons most likely to be involved in chemical reactions. Only S and P sublevels can have valence electron

Where on the periodic table would you find several elements with the same number of valence electrons

in the same column

What are the relationships among wavelength, frequency, and energy of electromagnetic radiation?

wavelength ↑ = frequency ↓ + energy ↓