Problem 48 - Chemistry: Principles and Reactions

Question

Give the symbol of the main-group metals in period 4 with the following number of unpaired electrons per atom. (Transition metals are not included.) (a) 0 (b) 1 (c) 2 (d) 3

Step-by-Step Solution

Answer

Question: Identify the main-group metals in period 4 with the following number of unpaired electrons per atom: (a) 0 unpaired electrons (b) 1 unpaired electron (c) 2 unpaired electrons (d) 3 unpaired electrons Answer: (a) 0 unpaired electrons: calcium (Ca) (b) 1 unpaired electron: potassium (K) (c) 2 unpaired electrons: germanium (Ge) (d) 3 unpaired electrons: arsenic (As)

Step 1: Identify the main-group metals in period 4

In period 4, the main-group metals we need to consider are: - potassium (K) - calcium (Ca) - gallium (Ga) - germanium (Ge) - arsenic (As) - selenium (Se) Note that gallium, germanium, arsenic, and selenium are considered metalloids, but for the purpose of this exercise, they are treated as main-group metals.

Step 2: Determine the electron configurations for the elements

We will determine the electron configurations of the main-group metals in period 4: - potassium (K): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ - calcium (Ca): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² - gallium (Ga): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p¹ - germanium (Ge): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p² - arsenic (As): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p³ - selenium (Se): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴

Step 3: Identify the number of unpaired electrons and the element they correspond to

Now we will count the number of unpaired electrons in each element: (a) 0 unpaired electrons - calcium (Ca): 4s² has no unpaired electrons. (b) 1 unpaired electron - potassium (K): 4s¹ has one unpaired electron. (c) 2 unpaired electrons - germanium (Ge): 4p² has two unpaired electrons. (d) 3 unpaired electrons - arsenic (As): 4p³ has three unpaired electrons. So, the main-group metals in period 4 with the given number of unpaired electrons per atom are: (a) 0 unpaired electrons: calcium (Ca) (b) 1 unpaired electron: potassium (K) (c) 2 unpaired electrons: germanium (Ge) (d) 3 unpaired electrons: arsenic (As)

Key Concepts

main-group elements

Main-group elements are those elements found in the s and p blocks of the periodic table. They encompass the first two groups and the last six groups, which include a majority of the let%27s features.%7D%0A%0A&group%types are typically metals, metalloids, and non-metals. For the purposes of certain exercises, elements can be categorized differently to simplify the learning process.

These elements are often explored because they tend to follow predictable patterns in terms of their electron configurations and chemical properties.

• They are characterized by having their valence (outermost) electrons in the s or p orbitals.
• This trait helps in determining the chemical bonding behavior and reactivity of the elements.

In period 4 of the periodic table, the main-group metals include elements like potassium (K) and calcium (Ca), but sometimes also include metalloids such as gallium (Ga), germanium (Ge), arsenic (As), and selenium (Se) when focusing on specific atomic characteristics.

Understanding main-group elements is pivotal because it lays the foundation for comprehending how elements interact chemically and are categorized in the periodic table. Main-group elements contribute significantly to diverse chemical reactions and compounds due to their varying electron arrangements.

periodic table

The periodic table is an organized chart where all known elements are listed. Each element is placed in a specific position based on its atomic number, electronic configuration, and recurring chemical properties.

The table's arrangement helps predict the properties of elements and how they might interact in chemical reactions. The rows of the table are called periods, and the columns are called groups. Main-group elements are found in specific groups within the periodic table, making navigation and prediction straightforward.

• Periods are horizontal rows which represent elements with the same number of electron shells.
• Groups are vertical columns that illustrate elements with similar chemical properties due to having the same number of valence electrons.

Each step across a period adds an electron to the outermost shell, affecting the chemical behavior. For period 4, this means starting from potassium (K) with only one electron in the 4s orbital, and continuing until krypton (Kr), with a filled 4p orbital. This periodic repetition of properties is key to the table's utility in chemistry.

By studying the periodic table, one can understand not just the elements themselves, but also the fundamental principles of chemistry and the science of atomic interactions.

unpaired electrons

Unpaired electrons are electrons in an atom that do not have a counterpart in the same orbital. They are crucial in determining the magnetic properties and reactivity of an element.

In electron configuration, these electrons are found in partially filled orbitals. The presence of unpaired electrons influences the atom's ability to form bonds and its chemical properties.

• Atoms with unpaired electrons are often paramagnetic, exhibiting a magnetic moment.
• The number of unpaired electrons can be determined by looking at the outermost electron configuration of an atom.

For instance, in the case of main-group metals in period 4, there's a variety in the number of unpaired electrons present.

- Potassium (K) has one unpaired electron in its 4s orbital.

- Germanium (Ge) exhibits two unpaired electrons in its 4p orbital.

- Arsenic (As) holds three unpaired electrons in its 4p orbital.

Unpaired electrons play a significant role in the specifics of how elements interact in chemical reactions, making them a central subject of study in understanding electron configuration and elemental behavior.