Question

Fill in the gaps in the following table, assuming each column represents a neutral atom. $$ \begin{array}{l|c|c|c|c|c} \hline \text { Symbol } & 159 & & & & \\ \text { Protons } & & 29 & & & 37 \\ \text { Neutrons } & & 34 & 53 & & \\ \text { Electrons } & & & 42 & 34 & \\ \text { Mass no. } & & & & 79 & 85 \\ \hline \end{array} $$

Short answer

Each column's 'Symbol' is 159, Cu, Mo, Se, Rb. Each gaps filled with atomic principles.

Step-by-step solution

Understanding the Concept

In a neutral atom, the number of protons equals the number of electrons. The mass number is the sum of protons and neutrons. This understanding will guide us in filling the gaps.

Filling 'Symbol' for Column 1

The atomic number, which is also the number of protons, is given as 159 for the first column. This does not match any known element since the periodic table does not extend to 159. Assuming it's a hypothetical element or a typo, the task doesn't give enough information to fill this gap. So we'll leave it as it is (Symbol = 159).

Completing 'Protons' for Column 3

For the column with 'Electrons' as 42, since the atom is neutral, 'Protons' must also be 42. Therefore, the element with the atomic number 42 is Molybdenum (Mo).

Completing 'Electrons' for Column 1

The symbol 159 implies protons are 159. For neutrality, electrons must also be 159.

Filling 'Symbol' for Column 2

In Column 2, given that 'Protons' is 29, corresponding to Copper (Cu). So, 'Symbol' for Column 2 is Cu.

Calculating 'Mass Number' for Column 2

With 'Protons' as 29 and 'Neutrons' as 34, the 'Mass Number' is calculated as 29 + 34 = 63.

Calculating 'Neutrons' for Column 4

In Column 4, 'Mass Number' is 79 and 'Electrons' (and hence 'Protons') are 34. The number of neutrons equals Mass number minus Protons, hence 79 - 34 = 45.

Filling 'Symbol' for Column 4

Since we previously identified the number of protons as 34, it corresponds to Selenium (Se). So, 'Symbol' is Se.

Completing 'Protons' and 'Electrons' for Column 5

Given 'Mass Number' is 85 and 'Neutrons' are unknown here. Since 'Protons' are given as 37 in last column, so 'Electrons' will also be 37 as the atom is neutral. The element with atomic number 37 is Rubidium (Rb), so 'Symbol' is Rb.

Key concepts

Neutral Atom

A neutral atom is one in which the number of protons equals the number of electrons. This balance maintains stability and neutrality in the atom's charge. Electrons are negatively charged, while protons carry a positive charge. Thus, for an atom to remain neutral, these opposite charges must be in equilibrium.
For instance, consider a neutral atom with 6 protons. It must also have 6 electrons to offset the positive charge of the protons and result in a net charge of zero. Understanding this principle helps in recognizing that:{"neutral_atom": "number of protons = number of electrons"}

Mass Number

The mass number of an atom is the sum of its protons and neutrons. These subatomic particles, found in an atom's nucleus, define its mass. While electrons also have mass, it is often negligible compared to protons and neutrons.
To calculate the mass number:

• Add the total number of protons.
• Add the total number of neutrons.

For example, if an atom has 8 protons and 8 neutrons, its mass number is 16. This value is essential for identifying isotopes of elements, which have the same atomic number but different mass numbers.

Atomic Number

An atom's atomic number is defined as the number of protons in its nucleus. This fundamental property determines the identity of an element. In fact, the periodic table is organized by increasing atomic number.
For example, hydrogen, the first element on the periodic table, has an atomic number of 1 because it has one proton. Helium, with an atomic number of 2, has two protons. This number not only identifies the element but also naturally informs the number of electrons in a neutral atom.

• Atomic number = Number of protons in an atom

Periodic Table

The periodic table is a systematic arrangement of elements based on their atomic number, electron configurations, and recurring chemical properties. It enables scientists and students alike to predict the behavior of elements and their compounds.

Key features of the periodic table include:

• Groups: Columns that organize elements with similar chemical behaviors.
• Periods: Rows representing elements with the same electron shell count.
• Element symbols and atomic numbers.

The layout of the table helps easily identify trends and predict the characteristics of elements. For example, elements in the same group often have similar valence electron configurations.

Element Symbols

Element symbols are abbreviated representations of the names of chemical elements, consisting of one or two letters. These symbols make it simpler to write and read chemical equations and compounds.
A few facts about element symbols include:

• Typically, the first letter is capitalized, and the second letter, if present, is lowercase.
• They are generally derived from the element's English or Latin name, such as "H" for hydrogen or "Na" for sodium (Latin: "Natrium").

These symbols are especially useful when working with the periodic table, as they provide a shorthand method to quickly identify and describe elements.