A scientist is working with an element that is a gas at room temperature and does not react with other elements. Which characteristic BEST describes this element?

• Metal

• Member of Group 18

• Metalloid

• Member of Group 2

Which statement BEST compares the properties of silicon (Si) and nickel (Ni)?

• Silicon is brittle, while nickel is malleable.

• Silicon is ductile, while nickel is not ductile.

• Silicon is a good conductor of electricity, while nickel is not.

• Silicon is liquid at room temperature, while nickel is solid at room temperature.

Mendeleev’s arrangement of elements is different than that of the modern periodic table. Based on Mendeleev’s arrangement, which elements should be placed in the shaded boxes labeled X and Z respectively?

• Indium (In), because it has a slightly higher atomic mass than aluminum (Al), and tin (Sn), because it has a slightly higher atomic mass than silicon (Si)

• Cadmium (Cd), because it has chemical properties similar to those of zinc (Zn), and mercury (Hg), because it has chemical properties similar to those of arsenic (As)

• Antimony (Sb), because it has a slightly higher atomic mass than zinc (Zn), and bismuth (Bi), because it also has a higher atomic mass than zinc (Zn)

• Gallium (Ga), because it has chemical properties similar to those of aluminum (Al), and germanium (Ge), because it has chemical properties similar to those of silicon (Si)

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Elements in a group of the periodic table are described below. Some Properties of a Certain Group of Elements: - Soft silvery-white color - Good conductor of thermal energy - Good conductor of electricity - Atoms contain a single valence electron These elements most likely belong to which group?

• Alkali metals

• Alkaline earth metals

• Halogens

• Noble gases

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Sodium, mercury, argon, and neon are used in the production of lamps. There are fewer safety guidelines regarding the handling of neon and argon than for mercury and sodium. Which of the following best describes the elements within the group of the periodic table that contains neon and argon gas?

• Gaseous at room temperature and highly reactive with metals

• Solid at room temperature and mildly reactive with strong acids

• Gaseous at room temperature and mostly unreactive with metals

• Solid at room temperature and mostly unreactive with strong acids

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Which of these statements is an accurate description of the ionization energies of elements in the periodic table?

• The ionization energy of lithium is greater than that of potassium.

• The ionization energy of iodine is greater than that of fluorine.

• The ionization energy of magnesium is greater than that of sulfur.

• The ionization energy of krypton is greater than that of neon.

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X-ray crystallography is a technique that allows scientists to determine the ionic and atomic radii of elements. Which of these statements correctly describes a trend in ionic or atomic radii in the periodic table?

• The ionic radius decreases from top to bottom in a group.

• The atomic radius increases from left to right across a period.

• The ionic radius remains constant from right to left across a period.

• The atomic radius increases from top to bottom in a group.

Which of the following elements has the smallest atomic radius?

• Sulfur

• Chlorine

• Aluminum

• Sodium

In a famous experiment conducted by Ernest Rutherford, positively charged alpha particles were scattered by a thin gold foil. Which of the following is a conclusion that resulted from this experiment?

• The nucleus is negatively charged.

• The atom is a dense solid and is indivisible.

• The mass is conserved when atoms react chemically.

• The nucleus is very small and the atom is mostly empty space.

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Based on his observations, the English chemist John Dalton formulated an atomic theory. Dalton’s Atomic Theory 1. All elements are made up of tiny indivisible particles called atoms. 2. Atoms of the same element are identical. The atoms of one element are different from the atoms of another element. 3. Atoms of different elements chemically combine to form chemical compounds. 4. During chemical reactions, atoms are rearranged. Atoms of one element cannot be changed into atoms of a different element as a result of a chemical change. In 1897, J. J. Thomson showed that negative charges could be made to move from one end of a cathode ray tube to another, causing the tube to glow. Because of this, Thomson is credited with the discovery of the electron. Based on this information, which part of Dalton’s atomic theory conflicted with Thomson’s new data?

• A 1

• B 2

• C 3

• D 4

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