Elements and Atoms - AP Chemistry

The metallic character of elements increases as you move down a group. All of the listed elements are in Group 5. Since is the furthest down, it must have the most metallic character.

When looking at a periodic table, you should notice that all of these elements are in the same period. Recall that atomic radii decrease as you move right on a period. Thus, this is the order of the elements by decreasing radius:

, or gallium, has the largest radius because it is the furthest left on the periodic table.

The correct answer is

has the most nonmetallic characteristics while has the most metallic characteristics. According to periodic trends, metallic character decreases from left to right across a period and increases top to bottom. Therefore, will show less metallic character than .

The atomic radii is the size of an atom when it is not bonded to any other atoms. The periodic table can be used to estimate the size of the atomic radii of atoms. As you move down the periodic table the atomic radii increase, but as you move from left to right on the periodic table, the size of the atomic radii decrease.

Sodium, aluminium, phosphorus, sulfur, and chlorine are all in the same row of the periodic table. Since the size of the atomic radii decreases as you move from left to right on the periodic table, the element furthest to the left will be the largest. Therefore, sodium is the largest atom out of the group.

The atomic radii is the size of an atom when it is not bonded to any other atoms. The periodic table can be used to estimate the size of the atomic radii of atoms. As you move down the periodic table the atomic radii increase, but as you move from left to right on the periodic table, the size of the atomic radii decrease.

Beryllium, magnesium, calcium, strontium, and barium are all in the same group on the periodic table, so the smallest element is the element closest to the top of the periodic table since the atoms become larger as you go down the periodic table. Therefore, the smallest atom of this group is beryllium.

Electronegativity refers to the ability of an atom to attract and bind electrons. If the valence electrons are less then half full, then it takes less energy to lose an electron than gain electron making these atoms less electronegative. If the valence electrons are more than half full, then it takes less energy to gain electrons compared to losing an electron; therefore these electrons are more electronegative. The periodic table can be used to predict the electronegativity of the atom and how it compares to other atoms. As you move left to right of the periodic table, the electronegativity increases because the atoms on the right side of the periodic table have more valence electrons, and smaller radii. As you move down the periodic table the electronegativity decreases because the atomic number increases resulting in a greater distance between valence electrons and the nucleus causing less pull on the valence electrons.

Using the electronegativity periodic trend, we can predict which of the atom's is most electronegative. Aluminium, silicon, phosphorous, sulfur, and chlorine are all in the same row in the periodic table. Therefore, chlorine is the most electronegative because it is the farthest right on the periodic table so it has the most valence electrons and it will cost less energy to gain an electron than lose an electron.

Electronegativity refers to the ability of an atom to attract and bind electrons. If the valence electrons are less then half full, then it takes less energy to lose an electron than gain electron making these atoms less electronegative. If the valence electrons are more than half full, then it takes less energy to gain electrons compared to losing an electron; therefore these electrons are more electronegative. The periodic table can be used to predict the electronegativity of the atom and how it compares to other atoms. As you move left to right of the periodic table, the electronegativity increases because the atoms on the right side of the periodic table have more valence electrons. As you move down the periodic table the electronegativity decreases because the atomic number increases resulting in a greater distance between valence electrons and the nucleus causing less pull on the valence electrons.

Using the electronegativity periodic trend, we can predict which of the atom's is least electronegative. Oxygen, sulfur, selenium, tellurium, and polonium are all in the same group of the periodic table. Therefore, polonium is the least electronegative because it is closest to the bottom of the periodic table and has the largest atomic numbers. Since polonium has the largest atomic number, there is a greater distance between the valence electrons and the nucleus resulting in a decreased pull on the valence electrons. Therefore, it is easier to lose a valence electron compared to atom's with a smaller atomic number.

de Broglie suggested that all matter has both wave-like and particle-like properties. His
equation states that λ= h/mv , where λ is the wavelength, m is mass, h is Planck’s constant,
and v is velocity. 4 mph is 1.8 m s−1 and Planck’s constant is 6.626e-34 kg m2 s−1 , giving
us a wavelength (λ) 4.6e-36 m ! A very small wavelength, indeed.

Rutherfords experiment focused a beam of alpha particles on a piece of gold foil. The result showed that most of the alpha particles passed through the foil, while a small fraction of particles were significantly deflected. This suggested the presence of a small, dense, positively charged nucleus. Most of the alpha particles passed through the electron clouds of the gold atoms, without impacting the nuclei, while those that did impact the nuclei were deflected by the positive charge of the nucleus.

Rutherford's experiment does not give us any concrete information about neutrons, nor does it allow us to assume that the number of protons and neutrons in the nucleus are equal.

In the Rutherford experiment, a beam of alpha particles was shot through a gold foil, with most of the particles flying straight through and a few scattering at angles greater than . These results suggest that most of the volume of foil was "empty" space, with small concentrations of positive charge, which we now know is the nucleus.

Ernest Rutherford made great advances in current understanding of atomic structure through his gold foil experiment. When firing positively-charged alpha particles at a thin film of gold atoms, most particles were found to pass straight through the film with little to no deflection, indicating that atoms were mostly composed of empty space. A few particles were deflected at large angles, indicating direct collisions with the positively charged nuclei of the atoms.

Recall that J.J. Thomson conducted the cathode ray tube experiment that proved the existence of a small negatively charged particle. Thomson was also able to determine the charge-to-mass ratio of an electron. Robert Millikan is the scientist who conducted the oil drop experiment, from which he was able to find the charge of the electron and deduce its mass using the electron's charge-to-mass ratio. Dalton was not involved in the discovery of the electron.

All the oil drops must have a charge that is a multiple of . If an oil drop is observed to have a charge of , that means the oil drop has three electrons. If an oil drop is observed to have a charge of , that means the oil drop has twelve electrons. If an oil drop is observed to have a charge of , that means the oil drop has two electrons.

To find the number of electrons this oil drop contains, divide the observed charge by the charge of a single electron.

This oil drop contains electrons.

Recall that J.J. Thomson conducted the cathode ray tube experiment that proved the existence of a small negatively charged particle. Thomson was also able to determine the charge-to-mass ratio of an electron. Robert Millikan is the scientist who conducted the oil drop experiment, from which he was able to find the charge of the electron and deduce its mass using the electron's charge-to-mass ratio.

From the cathode ray tube experiment, J.J. Thomson was only able to prove the existence of the negatively charged electron. From the results of the experiment, he also postulated that an atom was made up of a large spherical cloud of positive charge with negatively charged electrons embedded within. This model is also known as the plum pudding model.

E=hf, or E=hc/λ

h is Planck's constant with a value of 6.62606957 × 10-34 m2 kg / s. Converting 475nm to m gives 4.75x10-7m. c is the speed of light with 3x108m/s. Putting these variables into the second equation you get 4.174x10-19J

As the atomic radius decreases, electrons are drawn closer to the nucleus. Since the electromagnetic force between the positively charged nucleus and negatively charged electrons is a function of distance, the force of attraction, or effective nuclear charge, exerted on each electron will be greater.

To write out the shorthand electronic configuration for Ga, you simply write down the noble gas that that comes before , in this case , then write the rest of the electron configuration as normal.