writing: the atom what do you think you know about the structure of the atom?

Writing: The Atom

What do you think you know about the structure of the atom?

Atomic Structure

Standard 1h

• Students know the experimental basis for Thomson’s discovery of the electron, Rutherford’s nuclear atom, Millikan’s oil drop experiment, and Einstein’s explanation of the photoelectric effect.

J. J. Thomson

• In 1897 J. J. Thomson performed experiments from which he concluded that cathode rays are streams of negative, identical particles, which he named electrons.

J. J. Thomson

E. R. Rutherford• In 1913 E. R. Rutherford headed a

group that shot a beam of helium nuclei, or alpha particles, through a very thin piece of gold foil; the unexpectedly large deflections of some helium nuclei led to the hypothesis that the charged mass of each gold atom is concentrated in a small central nucleus.

E. R. Rutherford

Robert Millikan

• Robert Millikan confirmed Thomson’s conclusion that electrons are identical particles when he balanced tiny, electrically charged oil droplets between electric and gravitational fields and so discovered that the droplets always contained charge equal to an integral multiple of a single unit. He found out that the electron had a charge of -1 and it was about 2000 times lighter than the proton, and neutron.

Albert Einstein• Albert Einstein found he could explain

the photoelectric effect, in which light ejects electrons from metal surfaces, by proposing that light consists of discrete bundles of energy, or photons, each photon with an energy directly proportional to the frequency of the light, and by proposing that each photon could eject one and only one electron.

Albert Einstein• Photons with sufficient energy will eject

an electron whose kinetic energy is equal to the photon energy minus the energy required to free the electron from the metal. If the frequency of the light and therefore the energy of each proton is too low to free an electron, then merely increasing the light’s intensity (that is, merely producing more photons) does not cause electrons to eject.

Albert Einstein

Standard 1i

• Students know the experimental basis for the development of the quantum theory of atomic structure and the historical importance of the Bohr model of the atom.

Niels Bohr• Niels Bohr combined the concepts of

Rutherford’s nuclear atom and Einstein’s photons with several other ideas to develop a model that successfully explains the observed spectrum, or wavelengths, of electromagnetic radiation that is emitted when a hydrogen atom falls from a high energy state to a low energy state. In classical physics all accelerating charges emit energy. If electrons in an atom behaved in this way, light of ever-decreasing frequencies would be emitted from atoms.

Niels Bohr• Bohr explained why this phenomenon does not

occur when he suggested that electrons in atoms gain or lose energy only by making transitions from discrete energy levels. This idea was a key to the development of nonclassical descriptions of atoms. Louis de Broglie advanced the understanding of the nature of matter by proposing that particles have wave properties. On the basis of these ideas, Erwin Schrödinger and others developed quantum mechanics, a theory that describes and predicts atomic and nuclear phenomena.

Neils Bohr

Standard 1j

• Students know that spectral lines are the result of transitions of electrons between energy levels and that these lines correspond to photons with a frequency related to the energy spacing between levels by using Planck’s relationship (E = hv).

Standard 1j• The Bohr model gives a simple

explanation of the spectrum of the hydrogen atom. An electron that loses energy in going from a higher energy level to a lower one emits a photon of light, with energy equal to the difference between the two energy levels. Transitions of electrons from higher energy states to lower energy states yield emission, or bright-line, spectra.

Standard 1j• Absorption spectra occur when electrons

jump to higher energy levels as a result of absorbing photons of light. When atoms or molecules absorb or emit light, the absolute value of the energy change is equal to hc/λ, where h is a number called Planck’s constant, c is the speed of light, and λ is the wavelength of light emitted, yielding Planck’s relationship E = hv.

Neils Bohr

Standard 1i• The transition from the Bohr

model to the quantum mechanical model of the atom made us aware of the probabilistic nature of the distribution of electrons around the atom.

Standard 1i• A “dart board” made of concentric

rings can serve as a two-dimensional model of the three-dimensional atom. A graph as a function of radius of the number of random hits by a dart can be compared with a similar graph as a function of radius of the probability density of the electron in a hydrogen atom.

Standard 1e

• Students know the nucleus of the atom is much smaller than the atom yet contains most of its mass.

The Structure of the Atom

• The volume occupied by the nucleus of an atom is about one trillion times less than the whole atom.

• The diameter of an atom of any one of the elements is about 10,000 to 100,000 times greater than the diameter of the nucleus.

• The electrons occupy a large region of space centered around a tiny nucleus. so it is this region that defines the volume of the atom.

• The electron is almost 2,000 times lighter than the proton and neutron.

• 99% of the mass of the atom is in the nucleus

Structure of the Atom

Standard 1a

• Students know how to relate the position of an element in the periodic table to its atomic number and atomic mass.

Structure of the Atom

Standard 1g

• Students know how to relate the position of an element in the periodic table to its quantum electron configuration and to its reactivity with other elements in the table.

Electron Configuration• Each element has a unique electron

configuration (also known as quantum electron configuration) that determines the properties of the element.

• The quantum electron configuration tell you why the elements are organized the way they are in the periodic table, previously organized on the basis of chemical properties.

• Since the electrons are circling around in a huge empty space around the tiny nucleus, Neils Bohr proposed that the electrons have a position within that space.

• Neils Bohr proposed that the electrons are circling around in energy levels or quantum numbers.

Quantum Numbers• The main quantum numbers or

energy levels are 1, 2, 3, 4, 5, 6, and 7. They correspond to the periods, or horizontal rows, on the periodic table. • Within each quantum number or

energy level there are sub-shells of orbitals: s, p, d, and f. Each orbital can hold 2 electrons. There are rules for the sequence of orbital filling.

Electron Configuration

Rules for Quantum Numbers & Orbitals

• The first energy level or quantum number can hold only 2 electrons, and has only 1 s orbital that can hold a maximum of 2 electrons.

• The second energy level or quantum number can hold only 8 electrons, and has 1 s orbital, and 3 p orbitals that can hold a maximum of 6 electrons.

• The third energy level or quantum number can hold only 18 electrons, and has 1 s orbital, 3 p orbitals, and 5 d orbitals that can hold a maximum of 10 electrons.

• The fourth, fifth, sixth, and seventh energy level or quantum number can hold only 32 electrons, and has these subshells: 1 s orbital, 3 p orbitals, 5 d orbitals, and 7 f orbitals that can hold a maximum of 14 electrons.

• The electrons in the highest energy orbitals with the same principal quantum number are the valence electrons.

Element’s Electron Configuration• H- 1s1

• He- 1s2

• Li- 1s2 2s1

• Be- 1s2 2s2

• B - 1s2 2s22p1

• C- 1s2 2s22p2

• N- 1s2 2s22p3

• O- 1s2 2s22p4

• F- 1s2 2s22p5

• Ne- 1s2 2s22p6

• Na- 1s2 2s22p63s1

• Mg- 1s2 2s22p63s2

• Al- 1s2 2s22p6 3s23p1

• Si- 1s2 2s22p6 3s23p2

• P - 1s2 2s22p6 3s23p3

• S - 1s2 2s22p6 3s23p4

• Cl- 1s2 2s22p6 3s23p5

• Ar- 1s2 2s22p6 3s23p6

• K- 1s2 2s22p6 3s23p64s1

• Ca-1s2 2s22p6 3s23p64s2

Standard 1g• Sc-1s2 2s22p6 3s23p64s23d1

• Ti-1s2 2s22p6 3s23p64s23d2

• V-1s2 2s22p6 3s23p64s23d3

• Cr-1s2 2s22p6 3s23p64s23d4

• Mn-1s2 2s22p6 3s23p64s23d5

• Fe-1s2 2s22p6 3s23p64s23d6

• Co-1s2 2s22p6 3s23p64s23d7

• Ni-1s2 2s22p6 3s23p64s23d8

• Cu-1s2 2s22p6 3s23p64s23d9

• Zn-1s2 2s22p6 3s23p64s23d10

• Ga-1s2 2s22p6 3s23p64s23d104p1

Standard 1g• Ge-1s2 2s22p6 3s23p64s23d104p2

• As-1s2 2s22p6 3s23p64s23d104p3

• Se-1s2 2s22p6 3s23p64s23d104p4

• Br-1s2 2s22p6 3s23p64s23d104p5

• Kr- 1s2 2s22p6 3s23p64s23d104p6

• Rb- 1s2 2s22p6 3s23p64s23d104p65s1

• Sr- 1s2 2s22p6 3s23p64s23d104p65s2

• Y- 1s2 2s22p6 3s23p64s23d104p65s24d1

• Zr- [Kr] 1s2 2s22p6 3s23p64s23d104p65s24d2

Standard 1g• Nb-1s2 2s22p6 3s23p64s23d104p65s24d3

• Mo-1s2 2s22p6 3s23p64s23d104p65s24d4

• Tc-1s2 2s22p6 3s23p64s23d104p65s24d5

• Ru-1s2 2s22p6 3s23p64s23d104p65s24d6

• Rh-1s2 2s22p6 3s23p64s23d104p65s24d7

• Pd-1s2 2s22p6 3s23p64s23d104p65s24d8

• Ag-1s2 2s22p6 3s23p64s23d104p65s24d9

• Cd-1s2 2s22p6 3s23p64s23d104p65s24d10

• In-1s2 2s22p6 3s23p64s23d104p65s24d105p1

• Sn-1s2 2s22p6 3s23p64s23d104p65s24d105p2

• Sb-1s2 2s22p6 3s23p64s23d104p65s24d105p3

• Te-1s2 2s22p6 3s23p64s23d104p65s24d105p4

• I-1s2 2s22p6 3s23p64s23d104p65s24d105p5

Standard 1g• I-1s2 2s22p6 3s23p64s23d104p65s24d105p5

• Xe-1s2 2s22p6 3s23p64s23d104p65s24d105p6

• Cs-1s2 2s22p6 3s23p64s23d104p65s24d105p66s1

• Ba-1s2 2s22p6 3s23p64s23d104p65s24d105p66s2

• La-1s2 2s22p6 3s23p64s23d104p65s24d105p66s25d1

• Ce-1s22s22p63s23p64s23d104p65s24d105p66s24f15d1

• Pr-1s22s22p63s23p64s23d104p65s24d105p66s24f25d1

• Nd-1s22s22p63s23p64s23d104p65s24d105p66s24f35d1

• Pm-1s22s22p63s23p64s23d104p65s24d105p66s24f45d1

• Sm-1s22s22p63s23p64s23d104p65s24d105p66s24f55d1

• Eu-1s22s22p63s23p64s23d104p65s24d105p66s24f65d1

• Gd-1s22s22p63s23p64s23d104p65s24d105p66s24f75d1

Standard 1g• Tb-1s22s22p63s23p64s23d104p65s24d105p66s24f85d1

• Dy-1s22s22p63s23p64s23d104p65s24d105p66s24f95d1

• Ho-1s22s22p63s23p64s23d104p65s24d105p66s24f105d1

• Er-1s22s22p63s23p64s23d104p65s24d105p66s24f115d1

• Tm-1s22s22p63s23p64s23d104p65s24d105p66s24f125d1

• Yb-1s22s22p63s23p64s23d104p65s24d105p66s24f135d1

• Lu-1s22s22p63s23p64s23d104p65s24d105p66s24f145d1

• Hf-1s22s22p63s23p64s23d104p65s24d105p66s24f145d2

• Ta-1s22s22p63s23p64s23d104p65s24d105p66s24f145d3

• W-1s22s22p63s23p64s23d104p65s24d105p66s24f145d4

Standard 1g• Re-1s22s22p63s23p64s23d104p65s24d105p66s24f145d5

• Os-1s22s22p63s23p64s23d104p65s24d105p56s24f145d6

• Ir-1s22s22p63s23p64s23d104p65s24d105p56s24f145d7

• Pt-1s22s22p63s23p64s23d104p65s24d105p56s24f145d8

• Au-1s22s22p63s23p64s23d104p65s24d105p56s24f145d9

• Hg-1s22s22p63s23p64s23d104p65s24d105p56s24f145d10

• Tl-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p1

• Pb-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p2

• Bi-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p3

• Po-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p4

Standard 1g• At-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p5

• Rn-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p6

• Fr-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s1

• Ra-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s2

• Ac-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s26d1

• Th-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f16d1

• Pa-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f26d1

• U-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f36d1

• Np-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f46d1

• Pu-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f56d1

• Am-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f66d1

• Cm-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f76d1

• Bk-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f86d1

• Cf-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f96d1

• Es-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f106d1

• Fm-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f116d1

• Md-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f126d1

• No-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f136d1

• Lr-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f146d1

• Rf-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f146d2

• Db-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f146d3

• Sg-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f146d4

• Bh-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f146d5

• Hs-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f146d6

• Mt-1s22s22p63s23p64s23d104p65s24d105p56s24f145d106p67s25f146d7

Standard 1g

Standard 1g• Ge- [Ar 4s23d104p2

• As- [Ar] 4s23d104p3

• Se- [Ar] 4s23d104p4

• Br- [Ar] 4s23d104p5

• Kr- [Ar] 4s23d104p6

• Rb- [Kr] 5s1

• Sr- [Kr] 5s2

• Y- [Kr] 5s2 4d1

• Zr- [Kr] 5s2 4d2

Standard 1d

• Students know how to use the periodic table to determine the number of electrons available for bonding.

Standard 1d

Group 1 (Alkali Metals)

• Group 1 alkali metal elements have 1 valence electron. They lose one electron, thus they have a +1 charge, thus they have 1 electron available for bonding. Thus they are very reactive.

Group 2 (Alkaline Earth Metals)

• Group 2 alkaline earth metal elements have 2 valence electrons. They lose two electrons, thus they have a +2 charge, thus they have 2 electrons available for bonding.

Group 13 (Metal Elements)

•Group 13 metal elements have 3 valence electrons. They lose three electrons, thus they have a +3 charge, thus they have 3 electrons available for bonding.

Group 14 (Metal Elements)

•Group 14 elements have 4 valence electrons to share in a covalent bond, thus they have 4 electrons available for bonding.

Group 15• Group 15 elements have 5 valence

electrons. Thus they have 5 electrons available for bonding. Since they are nonmetals, they have high electronegativities, thus they steal 3 electrons from metal atoms in order to satisfy the octet rule of having 8 electrons in their valence shell. Thus they have a – 3 charge.

Group 16• Group 16 elements have 6 valence

electrons. Thus they have 6 electrons available for bonding. Since they are nonmetals, they have high electronegativities, thus they steal 2 electrons from metal atoms in order to satisfy the octet rule of having 8 electrons in their valence shell. Thus they have a -2 charge.

Group 17 Halogen Elements

• Group 17 halogen elements have 7 valence electrons. Thus they have 7 electrons available for bonding. Since they are nonmetals, they have high electronegativities, thus they steal 1 electrons from metal atoms in order to satisfy the octet rule of having 8 electrons in their valence shell. Thus they have a -1 charge. Thus they are very reactive.

Group 18 – Noble Gases

•Group 18 noble gas elements have 8 valence electrons. Thus they have 8 electrons, and do not need to form bonds with other elements.