Question

How many valence electrons does each of the following atoms have? a. titanium, \(Z=22\) b. iodine, \(Z=53\) c. radium, \(Z=88\) d. manganese, \(Z=25\)

Short answer

a. titanium: 4 valence electrons b. iodine: 7 valence electrons c. radium: 2 valence electrons d. manganese: 7 valence electrons

Step-by-step solution

Find the electron configuration for each element.

Using the periodic table, determine the electron configuration for each element. For this solution, we'll use the information of the atomic number: a. titanium, \(Z = 22\), electron configuration: 1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d² b. iodine, \(Z = 53\), electron configuration: 1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹⁰, 4p⁶, 5s², 4d¹⁰, 5p⁵ c. radium, \(Z = 88\), electron configuration: 1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹⁰, 4p⁶, 5s², 4d¹⁰, 5p⁶, 6s², 4f¹⁴, 5d¹⁰, 7s² d. manganese, \(Z = 25\), electron configuration: 1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d⁵

Determine the number of valence electrons.

Now, we can find the number of valence electrons by examining the outermost energy level of each element: a. titanium: 4s², 3d² - 4 valence electrons b. iodine: 5s², 4d¹⁰, 5p⁵ - 7 valence electrons c. radium: 7s² - 2 valence electrons d. manganese: 4s², 3d⁵ - 7 valence electrons So, each atom has the following number of valence electrons: a. titanium: 4 b. iodine: 7 c. radium: 2 d. manganese: 7

Key concepts

Electron Configuration

Electron configuration describes the distribution of electrons among the different energy levels and orbitals in an atom. It's like the seating plan for electrons in an atom, telling us where each electron "sits". Every element has a unique electron configuration that influences its chemical behavior. The electron configuration is typically written by noting the energy level (indicated by numbers) and the electron within each sublevel (indicated by letters like s, p, d, and f). For example, the electron configuration for titanium is \(1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^2\). This sequence follows the order in which electron orbitals fill with increasing atomic number.

• The Aufbau principle helps predict the electron configuration for most atoms.
• Hund's rule and the Pauli exclusion principle guide the arrangement of electrons within these orbitals.

By knowing the electron configuration, you can also determine the element's properties like valence electrons, which are key for chemical reactions.

Periodic Table

The periodic table is like the map of the chemical world. It organizes all known elements in a way that highlights their relationships. The table is organized into rows called periods and columns called groups. Elements are arranged in increasing order of atomic number from left to right and top to bottom. Each element's position can tell you a lot about it!

• Elements in the same group have similar properties and the same number of valence electrons.
• The table is divided into blocks corresponding to the s, p, d, and f sublevels where electrons are found.

For example, titanium, which sits in the d-block, has properties typical of transition metals. Learning the layout of the periodic table can greatly help in understanding and predicting chemical behavior of the elements.

Atomic Number

The atomic number is a defining trait of an element. It represents the number of protons in an atom's nucleus and also equals the number of electrons in a neutral atom. This is important because it determines the identity of the element. For example, titanium has an atomic number of 22, meaning it has 22 protons and 22 electrons.

• The atomic number increases as you move across the periodic table from left to right.
• It helps distinguish one element from another, defining the element's chemical properties.

Understanding the atomic number is crucial because it directly influences how electrons are arranged around the nucleus, affecting the element's electron configuration and, subsequently, its reactivity and bonding.

Chemical Elements

Chemical elements are fundamental substances consisting of only one type of atom, distinguished by their atomic number. Over 100 elements are known, each with unique properties and symbols. They are the building blocks of all matter, forming molecules and compounds through chemical reactions.

• Each element is represented by a one or two-letter symbol, like Ti for titanium or I for iodine.
• Elements are categorized by similar properties and are arranged in the periodic table based on increasing atomic number.

For instance, iodine, a halogen, has notable properties due to its atomic structure. Understanding elements is foundational in chemistry as they combine in countless ways to form the variety of substances we encounter daily.