Chem 9 Section 2 Assignments.

Use the periodic table to select the element that best fits each of the following descriptions. A group 5A element:

arsenic

Which element below has properties of both metals and nonmetals?

boron

Boron has an average atomic mass of 10.81. One isotope of boron has a mass of 10.012938 and a relative abundance of 19.80 percent. The other isotope has a relative abundance of 80.20 percent. What is the mass of that isotope? Report to two decimal places.

11.01 amu

Match each set of quantum numbers to the correct subshell description by typing in the correct number.

1: n = 2, l = 0 2p: ⇒ 4 2: n = 3, l = 2 3d: ⇒2 3: n = 1, l = 0 2s: ⇒ 1 4: n = 2, l = 1 4f: ⇒ 5 5: n = 4, l = 3 1s: ⇒ 3

Use the periodic table to identify the element indicated by each electron configuration by typing in the chemical symbol for the element.

1s2 2s2 2p6: Ne 1s2 2s2 2p6 3s2 3p3: P 1s2 2s2 2p6 3s2 3p6 4s1: K 1s2 2s2 2p6 3s2 3p6 4s2 3d8: Ni 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d3: Nb

Use the periodic to fill in the numbers in the electron configurations shown below. B: 1s2 2sA 2pB

A = 2 B = 1

Describe the photoelectric effect and explain why it made modifications to the Rutherford model necessary.

According to the Rutherford model, light of any energy should be able to make electrons leave the atom and be emitted. The energy of the emitted electrons should be related to the intensity of the light. Electrons are emitted only for certain wavelengths, and those wavelengths vary from atom to atom. The energy of the emitted electrons depends on the energy of the light, not its intensity.

Describe two ways the material in this lesson illustrates the importance of creativity in scientific investigations.

Dalton used creativity to modify Proust's experiment and interpret the results. Millikan used creativity to develop a way to measure the charge on an electron. Thomson used creativity to interpret the results of the cathode ray tube experiment. Rutherford used creativity to design an experiment to test the plum pudding model.

Compare the modern (electron cloud) model of the atom with Dalton's atomic model. Which of these statements describe the two models correctly? Check all of the boxes that apply.

Dalton's model represented atoms as indivisible, but the modern theory recognizes that they contain smaller particles. The modern model explains all available data about atoms; Dalton's model does not.

Identify one disadvantage to each of the following models of electron configuration: Dot structures Arrow and line diagrams Written electron configurations Type in your answer below.

Dot structures do not show the distribution of electrons in orbitals and take up a lot of space. Arrow and line diagrams take up a lot of space and make it difficult to count electrons. Written configurations make it easy to lose count of electrons and do not show the distribution of electrons in orbitals.

Identify one advantage to each of the following models of electron configuration: Dot structures Arrow and line diagrams Written electron configurations Type in your answer below.

Dot structures make it easy to count electrons and they show the number of electrons in each electron shell. Arrow and line diagrams show the spin of electrons and show every orbital. Written configurations require minimal space and show the distribution of electrons between subshells.

Use the periodic table to identify the element represented by each of the following electron configurations.

He]2s2: Be [Ne]3s23p5: Cl [Xe]6s1: Cs [Ar]4s23d9: Cu

Describe the main difference between the Bohr model and the electron cloud model of the atom.

In the Bohr model, an electron's position is known precisely because it orbits the nucleus in a fixed path. In the electron cloud model, the electron's position cannot be known precisely. Only its probable location can be known.

Scientists made the following two observations about emission spectra: Each element has a unique emission spectrum. Atoms emit energy only at specific wavelengths. Describe how the Bohr model explains both of these observations.

In the Bohr model, electrons can exist only in certain energy levels surrounding the atom. When electrons jump from a higher energy level to a lower one, they emit light at a wavelength that corresponds to the energy difference between the levels. The energy levels in each atom are unique.

Describe the main difference between the Bohr model of the atom and the Rutherford model.

In the Rutherford model, electrons can exist in any location outside the nucleus. In the Bohr model, electrons can exist only in certain energy levels surrounding the atom.

An atom of sodium-23 (Na-23) has a net charge of +1. Identify the number of protons, neutrons, and electrons in the atom. Then, explain how you determined the number of each type of particle. Use the periodic table to help you.

It contains 11 protons in the nucleus. It contains 12 neutrons in the nucleus. It contains 10 electrons surrounding the nucleus. The number of electrons are calculated from net charge and charge of proton (+1) and electron (-1). 13 neutrons are calculated from atomic number: 11 and mass number: 23.

Write a brief passage describing a neutral atom of nitrogen-14 (N-14). Describe the number of protons, neutrons, and electrons in the atom, where each type of particle is located, and how the terms atomic number, mass number, and atomic mass are related to the particles. Use the periodic table to help you.

It contains seven protons in the nucleus. It contains seven neutrons in the nucleus. It contains seven electrons in orbitals around the nucleus. Its atomic number is its number of protons. Its atomic mass is the mass of protons and neutrons.

What is the correct chronological order of scientists contributing to the modern periodic table?

Lavoisier, Dobereiner, Newlands, Mendeleev, and Moseley

Use the periodic table to determine the number of valence electrons in each of the following elements.

Na: 1 F: 7 V: 5 Ar: 8 C: 4

Explain how the atomic theory was modified from Dalton's theory to Rutherford's. Include an explanation of why the theory was modified.

Thomson's results showed that atoms contain smaller particles, so Dalton's theory had to be modified. Rutherford's results showed that most of an atom is empty space and that the mass is concentrated in the center of the atom. This discovery required the plum pudding model to be revised.

Use the periodic table to determine the electron configuration for Ca and Pm in noble-gas notation Ca:

[Ar]4s2

Use the periodic table to determine the electron configuration for Cl and Y in noble-gas notation. Y:

[Kr]5s2 4d1

Use the periodic table to determine the electron configuration for Cl and Y in noble-gas notation. Cl:

[Ne]3s2 3p5

Use the periodic table to determine the electron configuration for Ca and Pm in noble-gas notation Pm:

[Xe]6s2 4f 5

One of the following properties was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version. Which property fits this description?

atomic mass

Which element below is the most reactive?

chlorine

Use the periodic table to select the element that best fits each of the following descriptions. Which elements likely conduct electricity well? Check all that apply.

chromium calcium osmium

Use the periodic table to select the element that best fits each of the following descriptions. Halogen:

fluorine

Use the periodic table to select the element that best fits each of the following descriptions. Metalloid (semimetal):

germanium

Which element below is least reactive?

helium

Use the periodic table to select the element that best fits each of the following descriptions. Noble gas:

krypton

For the n = 3 electron shell, which of the following quantum numbers are valid? Check all that apply.

l = 0 m = -2 m = 2

Use the periodic table to select the element that best fits each of the following descriptions. Alkali metal:

lithium

Which of the following sets of quantum numbers describe valid orbitals? Check all that apply.

n = 1, l = 0, m = 0 n = 3, l = 0, m = 0 n = 5, l = 4, m = -3

Type in the maximum number of electrons that can be present in each shell or subshell below.

n = 5 shell: ⇒ 50 n = 2 shell: ⇒ 8 n = 2, l = 0 subshell: ⇒ 2 n = 2, l = 1 subshell: ⇒ 6 3d subshell: ⇒ 10 2s subshell: ⇒ 2 5f subshell: ⇒ 14

Use the periodic table to select the element that best fits each of the following descriptions. Which solution below most likely shows a vivid color?

nickel chloride

Which two elements most likely have the most similar properties?

nitrogen and phosphorus

Use the periodic table to select the element that best fits each of the following descriptions. Lanthanide:

promethium

Which element below must be stored in oil because of its reactivity?

sodium