Question

For each of the following elements, write its chemical symbol, locate it in the periodic table, give its atomic number, and indicate whether it is a metal, metalloid, or nonmetal: (a) chromium, (b) helium, (c) phosphorus, (d) zinc, (e) magnesium, (f) bromine, \((g)\) arsenic.

Short answer

a) Chromium (\(Cr\)): atomic number 24, metal. b) Helium (\(He\)): atomic number 2, nonmetal. c) Phosphorus (\(P\)): atomic number 15, nonmetal. d) Zinc (\(Zn\)): atomic number 30, metal. e) Magnesium (\(Mg\)): atomic number 12, metal. f) Bromine (\(Br\)): atomic number 35, nonmetal. g) Arsenic (\(As\)): atomic number 33, metalloid.

Step-by-step solution

Chemical Symbol

The chemical symbol of chromium is \(Cr\).

Atomic Number

Chromium has an atomic number of 24.

Classification

Chromium is classified as a metal. #b) Helium#

Chemical Symbol

The chemical symbol of helium is \(He\).

Atomic Number

Helium has an atomic number of 2.

Classification

Helium is classified as a nonmetal. #c) Phosphorus#

Chemical Symbol

The chemical symbol of phosphorus is \(P\).

Atomic Number

Phosphorus has an atomic number of 15.

Classification

Phosphorus is classified as a nonmetal. #d) Zinc#

Chemical Symbol

The chemical symbol of zinc is \(Zn\).

Atomic Number

Zinc has an atomic number of 30.

Classification

Zinc is classified as a metal. #e) Magnesium#

Chemical Symbol

The chemical symbol of magnesium is \(Mg\).

Atomic Number

Magnesium has an atomic number of 12.

Classification

Magnesium is classified as a metal. #f) Bromine#

Chemical Symbol

The chemical symbol of bromine is \(Br\).

Atomic Number

Bromine has an atomic number of 35.

Classification

Bromine is classified as a nonmetal. #g) Arsenic#

Chemical Symbol

The chemical symbol of arsenic is \(As\).

Atomic Number

Arsenic has an atomic number of 33.

Classification

Arsenic is classified as a metalloid.

Key concepts

Chemical Symbols

Understanding chemical symbols is fundamental in chemistry. These are abbreviations, often derived from either English or Latin names, used to represent elements on the periodic table. Each element has a unique one or two-letter symbol that stands for its name, making chemical equations and formulas more concise. For instance, the symbol for chromium is Cr, helium is He, and phosphorus is P. Learning these symbols is like learning the alphabet for the language of chemistry; it allows you to quickly identify and communicate about elements.

When consulting a textbook or solving exercises, it's crucial to memorize these symbols as they are the basic language of chemistry. A helpful tip is to use flashcards or to repeatedly write down the symbols alongside their corresponding elements to enhance recollection.

Atomic Number

The atomic number is another key concept in chemistry, denoting the number of protons found in the nucleus of an atom of the element. It is a unique identifier, as no two elements can have the same number of protons. The atomic number determines the identity of the element and its position on the periodic table. For example, helium has an atomic number of 2, indicating it has two protons, while arsenic has an atomic number of 33.

The atomic number is also crucial for understanding the arrangement of elements in the periodic table. Remember that the elements are arranged in order of increasing atomic number, which greatly helps in locating an element and predicting its properties.

Metals, Nonmetals, and Metalloids

Metals, nonmetals, and metalloids are categories used to classify the elements based on their physical and chemical properties.

• Metals typically are shiny, good conductors of heat and electricity, and are malleable (can be shaped). Examples from the exercise include chromium (Cr), zinc (Zn), and magnesium (Mg), which are all metals, recognizable by their tendency to lose electrons during reactions.
• Nonmetals are elements that are usually poor conductors of heat and electricity and can be gaseous, liquid, or solid at room temperature, such as helium (He), phosphorus (P), and bromine (Br).
• Metalloids possess mixed properties of both metals and nonmetals. One noteworthy example is arsenic (As), which can behave like a nonmetal under certain conditions and like a metal in others.

Familiarizing oneself with common characteristics of these groups can be helpful in predicting the behavior of elements and their compounds in chemical reactions.

Element Classification

The element classification system within the periodic table helps in comprehending chemistry at a more complex level. Elements are divided into groups based on similar properties, such as metals, nonmetals, and metalloids, as mentioned above. In addition, there are further subdivisions such as transition metals, halogens, noble gases, alkali metals, and alkaline earth metals.

Each classification has distinct properties and uses. For instance, halogens (like bromine) are very reactive nonmetals, while noble gases (like helium) are inert and unreactive. Transition metals, like zinc and chromium, are known for forming colorful compounds. Alkali metals are highly reactive, and alkaline earth metals are slightly less so.

Students can improve their understanding by practicing the location of these groups on the periodic table and studying their specific properties. This knowledge simplifies the prediction of how elements will react with others and is vital for students to progress in mastering chemistry.