Question

Identify the elements that correspond to the following atomic numbers. Label each as either a noble gas, a halogen, an alkali metal. an alkaline earth metal, a transition metal, a lanthanide metal, or an actinide metal. a. 17 e. 2 b. 4 f. 92 c. 63 g. 55 d. 72

Short answer

a. Chlorine (Cl) - Halogen b. Beryllium (Be) - Alkaline Earth Metal c. Europium (Eu) - Lanthanide Metal d. Hafnium (Hf) - Transition Metal e. Helium (He) - Noble Gas f. Uranium (U) - Actinide Metal g. Cesium (Cs) - Alkali Metal

Step-by-step solution

Identify Element

Element with atomic number 17 is Chlorine (Cl).

Determine Category

Chlorine (Cl) belongs to Group 17, which makes it a Halogen. #b. 4#

Identify Element

Element with atomic number 4 is Beryllium (Be).

Determine Category

Beryllium (Be) belongs to Group 2, which makes it an Alkaline Earth Metal. #c. 63#

Identify Element

Element with atomic number 63 is Europium (Eu).

Determine Category

Europium (Eu) belongs to the Lanthanide series, which makes it a Lanthanide Metal. #d. 72#

Identify Element

Element with atomic number 72 is Hafnium (Hf).

Determine Category

Hafnium (Hf) belongs to the d-block elements or transition metals. #e. 2#

Identify Element

Element with atomic number 2 is Helium (He).

Determine Category

Helium (He) belongs to Group 18, which makes it a Noble Gas. #f. 92#

Identify Element

Element with atomic number 92 is Uranium (U).

Determine Category

Uranium (U) belongs to the Actinide series, which makes it an Actinide Metal. #g. 55#

Identify Element

Element with atomic number 55 is Cesium (Cs).

Determine Category

Cesium (Cs) belongs to Group 1, which makes it an Alkali Metal.

Key concepts

Atomic Number

The atomic number is a crucial property of an element. It represents the number of protons present in the nucleus of an atom. This number is unique for each chemical element and defines the element's identity. For example, if an element's atomic number is 17, like Chlorine (Cl), it has 17 protons in its nucleus.

The atomic number is symbolized by the letter "Z" and plays a key role in arranging the elements in the periodic table. As you move across the table, the atomic number increases sequentially.

• This sequential increase correlates with an increase in protons, determining how elements react chemically.
• The concept of atomic number helps chemists predict element properties and their chemical behavior.

Understanding this concept lays the groundwork for diving deeper into the structure and reactivity of chemical elements.

Element Categories

The periodic table organizes elements into categories based on similar properties. These categories help scientists understand and predict the behavior of elements in chemical reactions.

There are several key categories, including noble gases, alkali metals, alkaline earth metals, halogens, lanthanides, actinides, and transition metals. Here's a brief overview of each group:

• Noble Gases: Found in Group 18, these elements are inert and highly stable. An example is Helium (He), atomic number 2.
• Alkali Metals: Located in Group 1, these are highly reactive, especially with water. Cesium (Cs), atomic number 55, is one such metal.
• Alkaline Earth Metals: Found in Group 2, they are also reactive but less so than alkali metals. Beryllium (Be), atomic number 4, is an example.
• Halogens: Situated in Group 17, these are reactive non-metals, like Chlorine (Cl), atomic number 17.
• Lanthanides: These rare earth metals are f-block elements, such as Europium (Eu), atomic number 63.
• Actinides: Also f-block elements, these heavy metals include Uranium (U), atomic number 92.
• Transition Metals: These lie in the d-block, known for their conductivity and forming colored compounds. Hafnium (Hf), atomic number 72, fits here.

Recognizing element categories aids in predicting how elements interact and form compounds.

Chemical Elements

Chemical elements are pure substances made of only one kind of atom. Each element is represented by a unique symbol, like H for Hydrogen or O for Oxygen.

These elements are the building blocks of all matter. Every substance you encounter is composed of combinations of different elements. The atomic number distinguishes each element from others by its number of protons. There are currently 118 recognized elements arranged in the periodic table.

• Some elements occur naturally, like Gold (Au) and Silver (Ag).
• Others are synthetic and produced in laboratories, such as Copernicium (Cn).

The study of elements and their interactions forms the basis of chemistry. Understanding elements allows scientists to develop new materials and discover various chemical processes.

Recognizing fundamental properties such as atomic number and categories can reveal much about an element's reactivity and usefulness.

Element Classification

Classification of elements in the periodic table is vital for understanding chemical properties and behaviors. This classification involves arranging elements in order based on their atomic number, forming a grid known as the periodic table.

This layout emphasizes periodicity or recurring trends in element properties. Elements in the same group (vertical columns) share similar chemical characteristics. For example, alkali metals like Sodium (Na) and Potassium (K) react vigorously with water.

• Period classification (horizontal rows) shows a gradual change in properties.
• Groups indicate elements with comparable configurations of their outer electrons, directly affecting reactivity.

The table's design captures the essence of periodic law: the properties of elements are periodic functions of their atomic numbers.

This systematic strategy helps scientists easily infer how substances may interact, predict unknown properties, and design novel materials fitted to specific needs.