Chemistry Chapter: Periodic Table and Electrons

Scientific activities should not only lead to social progress but also prioritize environmentally friendly practices.

Eco-friendly values should be integrated into all aspects of scientific research and practice.

The importance of environmental consideration should be explored at a deeper level during all scientific research and activities.

When pursuing scientific endeavors, a conscious effort should be made to ensure that the activities are eco-friendly in nature and do not cause harm to the environment.

The goal is to foster environmentally conscious scientific practices that promote both progress and sustainability.

The classification of elements in the periodic table is based on their atomic structure, specifically the number of protons in the nucleus, which defines the atomic number of an element.

Subshells are energy levels within a main energy level of an atom. They are named s, p, d, and f, and each subshell can hold a specific number of electrons.

The s subshell has only one orbital, which is spherical in shape. It can hold a maximum of two electrons.

The p subshell has three orbitals, each shaped like a dumbbell. It can hold a maximum of six electrons.

The d subshell has five orbitals and can accommodate a maximum of ten electrons.

The f subshell has seven orbitals and can hold a maximum of fourteen electrons.

An orbital is a three-dimensional region around the nucleus where there is a high probability of finding an electron. Each orbital can hold a maximum of two electrons.

The atomic number of an element determines its position and characteristics in the periodic table, based on the number of protons in its nucleus.

The arrangement of electrons in different energy levels and sublevels within an atom.

The outermost electron shell of an atom, containing the electrons that participate in chemical bonding.

The number of energy levels or shells in an atom is equal to the period number of the element in the periodic table.

Subshells are named based on their shapes and energies: s, p, d, and f. Each shell has a number of subshells equal to its shell number.

The maximum number of electrons that can be accommodated in a specific shell is calculated using the formula 2n², where n is the shell number.

The Bohr model, a simple explanation of atomic structure, was later found to have limitations due to new discoveries about the nature and positions of electrons.

Because of the complex nature of electron behavior, the Bohr model was replaced by models that incorporate sublevels and the concept of quantum numbers, providing a more accurate depiction of atomic structure.

The number of the outermost shell in an element's subshell electronic configuration.

The number of electrons in the outermost shell.

Groups 1 and 2 are in the s-block. Groups 3 to 12 are in the d-block. Groups 13 to 18 are in the p-block.

They are placed at the bottom of the periodic table in two separate rows because they are filling the 4f and 5f orbitals.

It helps in understanding the arrangement of elements based on their electron configuration.

The number of the shell in the subshell electronic configuration.

It tells you how many electrons are in the outermost shell, which is crucial for understanding an element's chemical behavior.

Elements in the same group have similar chemical properties.

Transition elements are found in groups 3 to 12 of the periodic table. Their last electron is filled in the penultimate shell, meaning the shell before the outermost shell.

In transition elements, even though the last electron enters a d subshell, the outermost shell still has electrons. This is different from normal elements where the outermost shell has all the valence electrons.

The subshell electronic configurations of transition elements are similar within a group and within a period. This means they have similar chemical properties.

The oxidation state of an element is the number of electrons gained or lost when it forms a chemical bond. Transition metals can have different oxidation states depending on the compound they are in.

Ferrous chloride (FeCl2) has Fe in +2 oxidation state, while ferric chloride (FeCl3) has Fe in +3 oxidation state.

The electronic configuration of an atom, such as Cr, where the d subshell is half filled, is considered more stable than a configuration with a partially filled d subshell.

The electronic configuration of an atom, such as Cu, where the d subshell is completely filled, is considered more stable than a configuration with a partially filled d subshell.

The subshell electronic configuration of an atom with a half-filled d subshell can cause changes in the filling of electrons to achieve stability. For example, Chromium's d subshell is half filled (d^5) instead of d^4 s^2.

The subshell electronic configuration of an atom with a completely filled d subshell can cause changes in the filling of electrons to achieve stability. For example, Copper's d subshell is completely filled (d^10) instead of d^9 s^2.

The maximum number of electrons that a d subshell can hold is 10.

The maximum number of electrons that an f subshell can hold is 14.

The number of shells present in the atom is equal to the highest principal quantum number (n) in the electronic configuration.

The electronic configuration of an atom gives us information about the subshells present in each shell. For example, 2s^2 indicates that the second shell has an s subshell.