The statement that is true for the long form periodic table is

All

The correct answer is option 4.All.

The long form periodic table, also known as the modern periodic table, provides a comprehensive and detailed understanding of the properties and behaviors of elements. Let's examine each statement to determine if it is true.

Let us explain each statement in detail to understand why all of them accurately describe the long form periodic table:

1. It reflects the sequence of filling the electrons in the order of sub energy levels s, p, d, and f.

The long form periodic table is structured based on the Aufbau principle, which dictates the order in which electron orbitals are filled. The sequence typically follows the pattern:

s-orbitals: Filled first, with a maximum of 2 electrons.

p-orbitals: Next, with a maximum of 6 electrons.

d-orbitals: Then, with a maximum of 10 electrons.

f-orbitals: Last, with a maximum of 14 electrons.

The table is divided into blocks (s-block, p-block, d-block, and f-block) that correspond to these sublevels, reflecting how electrons fill up in atoms. This arrangement helps in understanding the electronic configuration of elements and their position in the table.

2. It helps in predicting the valence states of the elements.

The group number of an element (for main group elements) often indicates the number of valence electrons. For example, Group 1 elements have 1 valence electron, Group 2 elements have 2, and so on up to Group 18. Knowing the number of valence electrons helps predict the chemical reactivity and the types of bonds an element can form. For instance, elements in Group 17 (halogens) typically gain one electron to achieve a stable configuration, often forming -1 ions.

3. It reflects trends in physical and chemical properties of the elements.

The periodic table exhibits several predictable trends:

Atomic Radius: Generally decreases across a period (left to right) and increases down a group.

Ionization Energy: Tends to increase across a period and decrease down a group.

Electronegativity: Increases across a period and decreases down a group.

Metallic Character: Decreases across a period and increases down a group.

Elements in the same group often exhibit similar chemical properties due to having the same number of valence electrons, leading to similar reactivity patterns. For example, alkali metals (Group 1) are highly reactive and readily lose one electron to form +1 ions.

Each of the statements highlights a different but crucial aspect of the long form periodic table's structure and utility:

1. Electron filling order: Reflects the underlying electronic structure.

2. Valence states prediction: Helps in determining how elements will react chemically.

3. Trends in properties: Allows for the prediction of both physical and chemical behavior across the table.

Thus, the correct answer is (4) All.