Question

If an atom has 104 electrons, 157 neutrons, and 104 protons, what is its approximate atomic mass? What is the name of this element?

Short answer

The approximate atomic mass is 261; the element is Rutherfordium (Rf).

Step-by-step solution

Understand Atomic Mass

The atomic mass of an atom is the sum of the number of protons and neutrons in its nucleus. Electrons have a negligible mass.

Calculate Atomic Mass

Since atomic mass is the sum of protons and neutrons, add 104 protons and 157 neutrons: \[ 104 + 157 = 261 \].

Identify the Element

The atomic number of an element (which defines the element) is the number of protons in the nucleus. An atom with 104 protons corresponds to the element Rutherfordium (Rf) on the periodic table.

Key concepts

Protons and Neutrons

In an atom's nucleus, we find protons and neutrons, two fundamental subatomic particles that play a crucial role in determining the atomic mass. The number of protons in the nucleus is important because it defines the element. For instance, one proton means hydrogen. Meanwhile, the number of neutrons can vary, leading to different isotopes of an element but not changing the element itself.
Protons carry a positive charge, while neutrons are neutral, meaning they have no charge. These particles together form most of the atom's mass because electrons have a much smaller mass compared to protons and neutrons.
When calculating atomic mass, you simply add up the number of protons and neutrons because they hold the mass of the atom. For example, if an atom has 104 protons and 157 neutrons, its approximate atomic mass would be the sum: \[ 104 + 157 = 261 \]. This is because each proton and neutron weighs roughly 1 atomic mass unit (amu).

Rutherfordium

Rutherfordium is an element on the periodic table associated with the atomic number 104. This means every atom of Rutherfordium has 104 protons in its nucleus. Named after the famous scientist Ernest Rutherford, this element belongs to the group of synthetic elements which means they are not found naturally on Earth but are created in laboratories.
Rutherfordium is a part of the transition metals series. The knowledge about its properties is limited due to its synthetic nature and short half-life, which means it decays quickly into other elements. Interesting to note, scientists use particle accelerators to create such elements by colliding lighter atoms to form heavier ones.
Although it is not an element we encounter in daily life, studying Rutherfordium helps scientists understand more about the behavior of heavy elements and provides insights into nuclear chemistry.

Periodic Table

The periodic table is a chart that organizes all known elements according to their atomic number, which is the number of protons in an atom. This information is crucial as it determines the chemical properties and behavior of each element.
The table is arranged in rows called periods and columns known as groups or families. Elements in the same group often have similar chemical properties. This is due to the way their electrons are arranged around the nucleus.
The periodic table is an invaluable tool in chemistry and physics. It helps predict the characteristics of elements, understand reactivity, and find relationships between elements. For example, knowing that Rutherfordium has 104 protons immediately tells us its position on the table and its group characteristics.

• Atomic number: Number of protons and electrons in a neutral atom.
• Group: Vertical columns, elements within a group share similar properties.
• Period: Horizontal rows, properties vary more significantly across them.

This comprehensive guide facilitates the study of matter and vastly enhances our understanding of the universe at an atomic level.