Problem 40 - Chemistry and Chemical Reactivity

Question

Give the name and chemical symbol for the following. (a) a nonmetal in the second period (b) an alkali metal (c) the third-period halogen (d) an element that is a gas at \(20^{\circ} \mathrm{C}\) and 1 atmosphere pressure

Step-by-Step Solution

Answer

(a) Oxygen (O); (b) Lithium (Li); (c) Chlorine (Cl); (d) Nitrogen (N)

Step 1: Identify Nonmetal in Second Period

In the periodic table, the second period includes the elements from Lithium (Li, atomic number 3) to Neon (Ne, atomic number 10). The nonmetals in this period are Boron (B, atomic number 5), Carbon (C, atomic number 6), Nitrogen (N, atomic number 7), Oxygen (O, atomic number 8), Fluorine (F, atomic number 9), and Neon (Ne, atomic number 10). Choose any one of these. Let's pick Oxygen: Name - Oxygen, Symbol - O.

Step 2: Identify Alkali Metal

Alkali metals are found in Group 1 of the periodic table. These include Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr). The first alkali metal is Lithium. Name - Lithium, Symbol - Li.

Step 3: Identify Third-Period Halogen

Halogens are located in Group 17 of the periodic table. In the third period, the halogen present is Chlorine. Name - Chlorine, Symbol - Cl.

Step 4: Identify Element that is Gas at 20°C and 1 atm

Under these conditions, the elements that are gases include Hydrogen (H), Nitrogen (N), Oxygen (O), Fluorine (F), Chlorine (Cl), and the noble gases Helium (He), Neon (Ne), and Argon (Ar). Any of these can be chosen. Let's pick Nitrogen: Name - Nitrogen, Symbol - N.

Key Concepts

Chemical Symbols

Chemical symbols are shorthand notations used to represent elements in the periodic table. Each chemical element has a unique chemical symbol, usually derived from its English or Latin name. For example, Oxygen is given the symbol "O," and Sodium is abbreviated as "Na" from the Latin word "Natrium."
These symbols allow chemists to write chemical equations and formulas with ease and are crucial for communication within science and education.
Understanding and recognizing these symbols is key to working with chemistry as they provide information on atomic composition and properties.

• Elements in the same family or group often share similar chemical properties and symbolism origins.
• The periodic table organizes elements by increasing atomic number, and each element has an atomic symbol next to it.

Nonmetals

Nonmetals are located towards the right side of the periodic table and have distinct properties compared to metals. They are usually poor conductors of electricity and heat and are more likely to gain electrons in chemical reactions.
Examples of nonmetals include Oxygen (O), Nitrogen (N), and Fluorine (F).
They are often gaseous at room temperature, although there are exceptions like Carbon, which can be solid in the form of graphite.

• Nonmetals can form covalent bonds by sharing electrons with other atoms.
• They are crucial for life, as elements like oxygen and carbon are integral to biological molecules.

Alkali Metals

Alkali metals are found in Group 1 of the periodic table and are characterized by their high reactivity, especially with water. They are soft, silvery metals and include elements like Lithium (Li), Sodium (Na), and Potassium (K).
Due to their single electron in the outermost shell, they readily lose this electron to form positive ions or cations.
Alkali metals are highly reactive and are rarely found in their pure form in nature.

• Reactivity increases as you move down the group from Lithium to Francium.
• They are stored under oil to prevent them from reacting with the moisture in the air.

Halogens

Halogens are located in Group 17 of the periodic table and include Fluorine (F), Chlorine (Cl), Bromine (Br), and Iodine (I). Known for their high reactivity, halogens often form salts when combined with metals.
They have seven electrons in their outermost shell, making them one electron short of a full noble gas configuration, which drives their reactivity and tendency to accept an electron.

• Halogens are diatomic molecules, meaning they naturally occur as pairs, like Cl₂.
• They are used in a variety of applications, from disinfectants to the making of pharmaceuticals.

Chlorine, for example, is a halogen present in the third period and is commonly used in water purification.