Chemistry-Unit 3: Investigating Patterns in the Periodic Table

How does the atomic radius change as you move left to right in Period 3 from aluminum through chlorine? Refer to the periodic table.

It generally decreases.

How does ionization energy change as you move left to right in Period 4 from potassium through iron? Refer to the periodic table.

It generally increases.

Which alkaline earth metal has the highest ionization energy? Refer to the periodic table.(a) barium (b) calcium (c) magnesium (d) strontium

barium

Which term describes the ability of an atom in a chemical compound to attract electrons from another atom in the compound?

electron affinity

Which term describes the energy required to remove an electron from an atom?

ionization energy

Which element has the lowest electronegativity? Refer to the periodic table. (a) carbon (b)fluorine (c)lithium (d) oxygen

lithium

Bromine, atomic number 35, belongs to Group 17. How many valence electrons does bromine have in its outermost shell? Refer to the periodic table.

7

Explain why a halogen bulb has a longer bulb life than a traditional incandescent bulb filled with argon.

Both types of bulbs have a tungsten filament that heats and causes the gas inside the bulb to glow. In a bulb filled with a halogen, the vaporized tungsten reacts with the halogen, which causes the tungsten to be redeposited onto the filament. This cyclic redepositing allows the tungsten filament to have a longer bulb life.

Explain how Mendeleev was able to predict the properties of undiscovered elements.

Mendeleev noticed a pattern in the properties of the elements when they were ordered by increasing mass. Gaps existed in the elements, but he was able to predict the properties of the missing elements by using the pattern in the properties of the known elements.

Which gas is unreactive according to its position in the periodic table? Refer to the periodic table. (a) carbon (b) neon (c) oxygen (d) sodium

Neon

Explain a similarity in the patterns through the periodic table between ionization energy and electronegativity. Refer to the periodic table.

Sample answers: * Both electronegativity and ionization energy increase as you move across a period in the periodic table from left to right. * Both electronegativity and ionization energy decrease as you move down a group in the periodic table.

Explain a difference between the periodic tables constructed by Mendeleev and Moseley.

Sample answers: * Mendeleev ordered the elements by atomic mass, while Moseley ordered the elements by nuclear charge/atomic number. * Moseley ordered the elements in a way that better fit the pattern of their properties. * Moseley's periodic table more closely resembles common modern periodic tables.

Explain why sodium and potassium have similar chemical properties. Refer to the periodic table.

Sodium and potassium are in the same group, and they have the same number of valence electrons. The same number of valence electrons gives them similar chemical properties.

Which statement is the best reason why the atomic radius generally increases with atomic number in each group of elements?

The number of occupied shells increases.

Which element is most similar in behavior to calcium? Refer to the periodic table. (a) chlorine (b) magnesium (c) sodium (d) sulfur

magnesium