Chemistry Class: Periodic Table & Trends

The organization of elements based on their properties and atomic numbers, arranged in rows (periods) and columns (groups).

The principle that states the chemical and physical properties of elements repeat periodically when arranged by increasing atomic number.

The number of elements in each period of the periodic table (e.g., 2, 8, 8, 18, 18, 32).

The process of classifying elements based on their similarities in chemical and physical properties.

The change in a property of elements as you move across a period or down a group on the Periodic Table.

Döbereiner's observation that groups of three elements (triads) share similar chemical properties.

Newland's observation that every eighth element in a period displays similar properties.

Mendeleev's initial attempt to organize the periodic table based on atomic mass, leading to a few limitations.

The energy required to remove one electron from a neutral gaseous atom in its ground state.

Beryllium's outermost electron is in the s orbital, which is more strongly attracted to the nucleus than boron's outermost electron in the p orbital.

Nitrogen has a half-filled p orbital, which is more stable than oxygen's partially filled p orbital.

The change in energy when an electron is added to a neutral gaseous atom.

Halogens have very high negative electron gain enthalpy because they only need one more electron to achieve a full outer shell, making them very stable.

Electron gain enthalpy generally becomes less negative down a group because the outermost electron is further from the nucleus, decreasing the attraction.

The ability of an atom to attract shared electrons in a compound.

Electronegativity increases across a period from left to right due to increasing nuclear charge, resulting in a stronger attraction for electrons.

The charge acquired by an atom when it forms a compound. It reflects the number of electrons gained or lost.

Alkali metals have high reactivity because they readily lose one electron to achieve a stable octet configuration.

d-block elements are a group of elements in the periodic table whose last electron enters the d-orbital, even though the 4s orbital fills first due to the order of increasing energy levels.

Transition metals form a bridge between s-block and p-block elements.

The general electronic configuration for d-block elements is (n-1)d1-10 ns0-2, where n represents the principal quantum number.

f-block elements are those in which the last electron enters an f-orbital and are also known as inner transition elements.

The general electronic configuration for f-block elements is (n-2)f1-14 (n-1)d0-2 ns2, where n represents the principal quantum number.

For s-block elements, the group number equals the number of valence electrons. For p-block elements, the group number is 10 plus the number of valence electrons. For d-block elements, the group number is the total number of electrons in the (n-1) d sub-shell plus the number of valence electrons.

Most elements in the periodic table are metals, including s-block, d-block, and f-block elements. p-block contains metals, non-metals, and metalloids.

Metalloids are elements that exhibit both metallic and non-metallic properties.

Metallic character refers to an element's tendency to lose electrons.

Non-metallic character refers to an element's tendency to gain electrons.

Metallic character increases down a group because the valence electrons are further from the nucleus and easier to lose.

Metallic character decreases across a period because the nuclear charge increases, pulling the valence electrons closer to the nucleus, making them harder to lose.

Atomic radius is a measure of the size of an atom, defined as half the distance between the centers of two adjacent atoms of the same element.

Atomic radius decreases across a period because the nuclear charge increases, pulling the electrons closer to the nucleus.

Atomic radius increases down a group because the number of electron shells increases, making the atoms larger.

A temporary name given to a newly discovered element based on its atomic number.

The number of shells in an atom is determined by the highest value of the principal quantum number. Elements in the same period have the same number of atomic orbitals and electron shells.

Elements in the same group share the same number of valence electrons and similar chemical properties, but have different principal quantum numbers.

The outermost shell electrons determine an element's chemical behavior and are crucial for bonding. Different elements in the same group have different energy levels for their valence electrons.

The s-block of the periodic table includes Groups 1 and 2, which are the alkali metals and alkaline earth metals, respectively.

Alkali metals are soft, highly reactive metals with low melting points. They form strongly basic oxides and exist as monovalent cations (positive charge).

Alkaline earth metals are harder, less reactive, and have higher melting points than alkali metals. They form less basic oxides and exist as divalent cations (positive charge).

Elements in which the last electron enters the p-orbital. They encompass groups 13 to 18, and include various types of elements.

The final electron goes into the d-orbital, which is an inner shell. They are located in Groups 3 to 12, and include transition metals.

The last electron enters the f-orbital. They are called inner transition elements and include lanthanides and actinides.

s-block and p-block elements are collectively called the 'main group' elements or 'representative elements'.

The general electronic configuration of s-block elements is ns1 or ns2, meaning the last electron enters the s orbital.

The general electronic configuration of p-block elements varies from ns2 np1 to ns2 np6, with the last electron entering the p orbital.

The electronic configuration of d-block elements involves the last electron entering the d-orbital, which is an inner (not the outermost) orbital.