Atomic Structure and the Periodic Table - Vocabulary (Video Notes)

Vocabulary flashcards covering key terms from the notes on the periodic table, atomic structure, isotopes/ions, and mixtures, along with separation techniques and common compounds.

Periodic Table

A tabular arrangement of elements in order of increasing atomic number, showing periodic patterns in properties.

Newlands

1870s chemist who arranged known elements by atomic weight, noticing periodic patterns but with problems due to undiscovered elements.

Mendeleev

Chemist who created a periodic table with gaps for future elements in 1869 and reordered some elements; later shown to be ordered by atomic number.

Group

A vertical column in the periodic table; elements in a group have similar properties due to similar electron configurations.

Group 0 / Noble gases

Elements with full outer electron shells; very unreactive; helium has 2 outer electrons, others typically 8.

Noble gases

Another term for Group 0 elements, known for chemical inertness and stable electron configurations.

Group 1 / Alkali metals

Elements with one electron in the outer shell; low melting/boiling points that decrease down the group; highly reactive.

Alkali metals

Group 1 metals; stored under oil because they react vigorously with air and moisture.

Group 7 / Halogens

Non-metals with seven electrons in the outer shell; reactivity decreases down the group; form salts with metals by gaining one electron.

Halogens

Group 7 non-metals that react with metals to form ionic salts by gaining an electron.

Electron configuration

Arrangement of electrons in the shells around the nucleus; first shell holds up to 2 electrons, next shells up to 8.

Atomic number

Number of protons in the nucleus; defines the element and its position in the periodic table.

Mass number

Sum of protons and neutrons in the nucleus.

Isotope

Atoms of the same element (same protons) with different numbers of neutrons and mass numbers.

Ion

Atom that has gained or lost electrons, giving it a net electric charge.

Proton

Positively charged subatomic particle with mass ~1; located in the nucleus.

Neutron

Electrically neutral subatomic particle with mass ~1; located in the nucleus.

Electron

Negatively charged subatomic particle with very small mass; orbits the nucleus in shells.

Nucleus

Tiny central region of the atom containing protons and neutrons; contains most of the atom’s mass.

Plum-pudding model

Early atomic model proposed by Thomson: electrons embedded in a positively charged 'soup'.

Atomic radius

Typical size of an atom; about 0.1 nm (1 x 10^-10 m); nucleus is much smaller than the atom.

Sodium electron configuration (2,8,1)

Example of electron arrangement for Na; two electrons in the first shell, eight in the next, one in the outer shell.

Sodium oxide (Na2O)

Example of a compound formed by a Group 1 metal with oxygen.

Atom

The smallest unit of an element that can exist; basic building block of matter.

Element

Substance that contains only one sort of atom and is represented in the periodic table.

Compound

Substance formed from two or more elements chemically combined in fixed proportions.

Mixture

Substances made of two or more elements or compounds that are not chemically bonded; components retain properties.

Chemical formula

Notation showing which elements and how many atoms are in a molecule (e.g., H2O, CaCO3).

Reactants

Substances that react in a chemical equation; on the left side.

Products

New substances formed in a chemical reaction; on the right side.

Conservation of mass

Mass of products equals mass of reactants in a closed system; atoms are rearranged, not created or destroyed.

Filtration

Physical separation of insoluble solids from a liquid by passing through a filter.

Crystallisation

Obtaining a pure solid from a solution by evaporation or cooling to form crystals.

Simple distillation

Separating a solvent from a solution by heating and collecting the distillate.

Fractional distillation

Separating components with different boiling points using a fractionating column.

Chromatography

Separating soluble components of a mixture based on different movement through a stationary phase and solvent.

pH probe

Instrument used to measure the acidity or basicity of a solution.

Water (H2O)

A molecule composed of two hydrogen atoms and one oxygen atom; example of a compound.

Displacement (halogens)

A more reactive halogen can displace a less reactive halogen from its salt solution.

Magnesium oxide (MgO)

Compound formed when magnesium burns in oxygen; example of a simple oxide.