Problem 94 - Chemistry Matter and Change

Question

If a nucleus contains 12 protons, how many electrons are in the neutral atom? Explain.

Step-by-Step Solution

Answer

A neutral atom has an equal number of protons and electrons. Since the nucleus contains 12 protons, the number of electrons in the neutral atom must also be 12.

Step 1: Understand the concept of a neutral atom.

A neutral atom has no net electrical charge because the number of protons, which are positively charged particles, is equal to the number of electrons, which are negatively charged particles.

Step 2: Given the number of protons in the nucleus.

We are given that the nucleus contains 12 protons. This information can help us determine the number of electrons in the neutral atom.

Step 3: Determine the number of electrons in the neutral atom.

Since the atom is neutral, the number of protons equals the number of electrons. Therefore, the atom contains 12 electrons.

Step 4: Explanation.

The neutral atom contains 12 electrons because, in a neutral atom, the number of protons and electrons is always equal. In this case, the nucleus contains 12 protons, making the atom neutral by having an equal number of electrons, which is 12.

Key Concepts

Protons

Protons are essential components of an atom's nucleus and are critical in determining an element's identity. They are positively charged particles, and each proton carries a charge of "+1". The number of protons in the nucleus is known as the atomic number, which is unique for each element and determines its position in the periodic table.

• For example, an atom with 12 protons is magnesium, as its atomic number is 12.
• The protons define the chemical element and influence chemical behavior.

In a neutral atom, the positive charges from protons are balanced by an equal number of negatively charged electrons. Protons remain fixed within the nucleus, contributing to most of the atom's mass.

Electrons

Electrons are tiny subatomic particles that orbit the nucleus of an atom in varying energy levels. These particles carry a negative electrical charge of "-1". In a neutral atom, electrons balance the positive charge of protons to ensure that the atom has no net electrical charge. Each electron's mass is significantly smaller compared to protons, contributing minimally to the atom's total mass.

• Electrons are crucial in chemical bonding and reactions due to their ability to be shared or exchanged between atoms.
• Electrons occupy different orbitals at varying distances from the nucleus, determining the chemical properties of an atom.

For a neutral atom with 12 protons, 12 electrons will circle the nucleus, creating a balance of charge.

Electrical Charge

Electrical charge is a fundamental property of particles that causes them to experience a force when near other electrically charged particles. Atoms are mostly neutral because they contain equal numbers of protons and electrons. This balance in a neutral atom results in a net electrical charge of zero.

• Charge interactions follow the principle that like charges repel, while opposite charges attract.
• Atoms become charged, either positively or negatively, when there are unequal numbers of protons and electrons.

For instance, when an atom loses an electron, it gains a positive charge and becomes a cation. Conversely, gaining an extra electron results in a negative charge, forming an anion. However, in the case of a neutral atom with 12 protons and 12 electrons, the electrical charges perfectly cancel each other out, leaving the atom electrically neutral.