Chemistry Chapter 6: The Periodic Table

The idea that when elements are arranged in order of increasing atomic number, there is a repeating pattern in their physical and chemical properties.

Horizontal rows of elements in the periodic table. Each row represents elements with the same number of electron shells.

Vertical columns of elements on the periodic table with similar chemical properties because they have the same number of valence electrons. There are 18 groups.

A Russian chemist who arranged elements in order of increasing atomic mass, creating the first periodic table.

A British physicist who rearranged elements in the periodic table by atomic number, making it more accurate.

The arrangement of elements in the periodic table based on their atomic number, which results in a periodic repetition of their properties.

A set of three elements with similar properties, where the middle element has properties in between the other two. This was an early attempt at organizing elements.

The atomic number of an element is the number of protons in its nucleus. It determines the element's identity and its position on the periodic table.

Elements that are good conductors of heat and electricity, have luster, are malleable and ductile. Examples include copper, gold and iron.

Elements that are poor conductors of heat and electricity, are typically brittle, and may be gases, liquids or solids.

Elements that have properties that fall in between metals and nonmetals.

The outermost energy level of an atom that contains electrons. The number of valence electrons determines an element's reactivity.

A group of elements in the periodic table that have similar chemical properties due to having the same number of valence electrons, and thus react in similar ways.

A horizontal row of elements in the periodic table. Elements in the same period have the same number of electron shells.

Elements located in groups 1A through 7A or 1, 2, 13-17 on the periodic table. They have a wide range of reactivity and are essential for many biological and industrial processes.

Elements in groups 1A and 2A of the periodic table, known for being highly reactive and readily losing electrons to form positive ions.

All elements in the same vertical column of the periodic table have the same number of valence electrons, resulting in similar chemical behavior.

The electrons in the inner energy levels of an atom, not involved in chemical bonding. They are closer to the nucleus and shielded from external interactions.

Atoms gain or lose electrons to achieve a stable, noble gas configuration. This results in the formation of positively charged ions (cations) or negatively charged ions (anions).

The process of atoms gaining or losing electrons to become ions.

Group 1 elements in the periodic table, characterized by having one valence electron.

Group 2 elements in the periodic table, characterized by having two valence electrons. They are less reactive than alkali metals.

Group 18 elements in the periodic table, characterized by having a full outer shell of electrons (octet). This makes them very stable and unreactive.

The amount of energy required to remove one electron from a gaseous atom.

The energy required to remove the second electron from a gaseous atom.

Always greater than the first ionization energy.

The amount of energy required to remove the third electron from a gaseous atom.

The greater the nuclear charge (protons), the greater the ionization energy.

The more occupied energy levels (shells) between the nucleus and outer electrons, the lower the ionization energy.

As you go down a group in the periodic table, the first ionization energy decreases.

As you go across a period in the periodic table, the ionization energy generally increases.

A measure of the size of an atom, defined as half the distance between the nuclei of two identical atoms bonded together.

The tendency of an atom to attract electrons towards itself when it is forming a chemical bond.

The energy required to remove one electron from a neutral gaseous atom.

The distance between the nucleus and the outermost electron in an ion.

Elements in the same vertical column of the periodic table, characterized by similar chemical properties due to having the same number of valence electrons.

Elements in the same horizontal row of the periodic table, characterized by varying chemical properties as they move across the table.

The amount of energy required to remove one mole of electrons from one mole of gaseous atoms in their ground state.

The outermost energy level of an atom, containing the valence electrons.

A measure of the attraction between the nucleus and the valence electrons.

The distance between the nucleus and the outermost electrons.

As you move across a period, the first ionization energy generally increases.

As you move down a group, the first ionization energy generally decreases.

The first ionization energy of the elements generally increases as you move across a period, with some exceptions due to electron configuration.

The first ionization energy of the elements generally decreases as you move down a group, due to the increasing distance between the nucleus and the valence electrons.

The first ionization energy is generally lower for elements with half-filled or fully-filled subshells due to their greater stability.

The first ionization energy of nitrogen is lower than that of oxygen because the removal of an electron from nitrogen results in a half-filled p subshell, which is more stable.

The first ionization energy of fluorine is higher than that of oxygen because the removal of an electron from oxygen results in a more stable electron configuration, with two electrons in each p orbital.

As you move across a period, the electronegativity generally increases.

As you move down a group, the electronegativity generally decreases.