Atoms, Elements, Compounds and the Periodic Table

A set of flashcards covering key concepts about atoms, elements, compounds, and the periodic table.

What is an atom?

An atom is the smallest identifiable part of any chemical element, consisting of a nucleus containing protons and neutrons, orbited by electrons.

What is an element?

An element is a substance made up of atoms, all containing the same number of protons.

What is a compound?

A compound is a substance that contains two or more different elements chemically combined in a fixed proportion.

What is the chemical formula for Carbon Dioxide?

CO₂

What is the chemical formula for Sodium Carbonate?

Na₂CO₃

What is the chemical formula for Hydrochloric Acid?

HCl

What is the difference between a compound and a mixture?

Compounds are chemically bonded while mixtures are physically combined without chemical bonding.

Define solute.

The substance that is dissolved in a solvent to create a solution.

Define solvent.

The liquid in which a solute is dissolved.

Define soluble.

Able to be dissolved, typically in water.

Define insoluble.

Unable to be dissolved.

What is the process of filtration?

A method to separate an insoluble solid from a liquid using a funnel and filter paper.

What is the process of crystallisation?

A method to separate a soluble solid from a liquid by evaporating the solvent.

What is chromatography?

A technique used to separate a mixture of miscible liquids by drawing the solvent up a piece of filter paper.

What is relative atomic mass?

An average mass that considers the masses and abundances of all isotopes of an element.

What are the relative charges and masses of protons, neutrons, and electrons?

Proton: charge +1, mass 1; Neutron: charge 0, mass 1; Electron: charge -1, mass negligible (1/1840).

What is an isotope?

Different forms of the same element with the same number of protons but differing numbers of neutrons.

What is the atomic number of an element?

The number of protons in the nucleus of an atom.

What is the mass number of an element?

The sum of protons and neutrons in the nucleus of an atom.

Describe Döbereiner’s Triads.

Elements with similar chemical properties often occur in groups of three, where the average atomic mass of the first and third element equals the atomic mass of the second.

What is the law of octaves according to Newlands?

The observation that every eighth element shares similar properties when arranged by increasing atomic mass.

What characterizes the noble gases?

Noble gases are unreactive and have full outer shells, with boiling points lower than room temperature.

What types of ions do metals form?

Metals typically form positive ions, or cations.

What types of ions do non-metals form?

Non-metals typically form negative ions, or anions.

How do transition metals differ from alkali metals?

Transition metals have higher melting points, greater density, and form ions with various charges, whereas alkali metals have lower melting points and form only +1 ions.