Ch.2 - Atoms & Elements

Problem 74

Chapter 2, Problem 74

Classify each element as an alkali metal, alkaline earth metal, halogen, or noble gas. a. F b. Sr c. K d. Ne e. At

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Identify the group in the periodic table to which each element belongs. This can be done by referring to a periodic table where elements are grouped primarily by their electron configurations and similar properties.

Classify element 'F' (Fluorine) by noting it is in Group 17, which is known for halogens. Halogens are nonmetals with seven valence electrons, making them highly reactive.

Classify element 'Sr' (Strontium) by observing it is in Group 2. Elements in this group are called alkaline earth metals and are characterized by having two valence electrons.

Classify element 'K' (Potassium) by locating it in Group 1. Elements in this group are known as alkali metals, which have a single valence electron and are highly reactive, especially with water.

Classify element 'Ne' (Neon) and 'At' (Astatine) by noting that Neon is in Group 18, which contains noble gases known for being inert due to having full valence electron shells, and Astatine is in Group 17, making it a halogen.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Periodic Table Groups

The periodic table is organized into groups that categorize elements based on similar properties. Alkali metals (Group 1) are highly reactive and include elements like potassium (K). Alkaline earth metals (Group 2) are also reactive but less so than alkali metals, such as strontium (Sr). Halogens (Group 17) are nonmetals known for their reactivity, including fluorine (F) and astatine (At). Noble gases (Group 18) are inert and do not readily react with other elements, with neon (Ne) being a prime example.

Reactivity of Elements

The reactivity of elements varies significantly across the periodic table. Alkali metals are characterized by their tendency to lose one electron, making them very reactive, especially with water. Halogens, on the other hand, are highly reactive nonmetals that tend to gain an electron to achieve a stable electron configuration. Noble gases are unique in that they have a full valence shell, which makes them largely unreactive under standard conditions.

Element Classification

Elements can be classified into distinct categories based on their properties and positions in the periodic table. Alkali metals and alkaline earth metals are both metals but differ in their reactivity and electron configurations. Halogens are nonmetals with high electronegativity, while noble gases are characterized by their complete valence electron shells. Understanding these classifications helps in predicting the behavior and interactions of different elements.

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Write the symbol for each element and classify it as a metal, nonmetal, or metalloid. a. bromine b. potassium c. lead d. silicon e. silver

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Determine whether or not each element is a transition element. a. Cr b. Br c. Mo d. Cs

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Which pair of elements do you expect to be most similar? Why? a. nitrogen and oxygen b. titanium and gallium c. lithium and sodium d. germanium and arsenic e. argon and bromine

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Textbook Question

The atomic mass of fluorine is 18.998 amu, and its mass spectrum shows a large peak at this mass. The atomic mass of chlorine is 35.45 amu, yet the mass spectrum of chlorine does not show a peak at this mass. Explain the difference.

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