Definitions For Topic 1 Key Concepts In Chemistry⬆️ Flashcards
What is an anion?
A negatively charged ion formed when an atom gains at least one electron.
Anions are often involved in ionic compounds and play a key role in chemical reactions.
Define an atom.
The smallest part of an element that can exist, and all substances are made up of atoms.
Atoms consist of a nucleus surrounded by electrons.
What is the atomic nucleus?
A positively charged object composed of protons and neutrons at the center of every atom with electrons orbiting it.
The atomic nucleus contains most of the atom’s mass.
What does atomic number indicate?
The number of protons in the nucleus.
The atomic number uniquely identifies an element.
What is Avogadro’s constant?
The number of atoms, molecules, or ions in a mole of a given substance.
Avogadro’s constant is approximately 6.022 x 10^23.
Define a cation.
A positively charged ion formed when an atom loses at least one electron.
Cations are typically formed from metals in chemical reactions.
What is a compound?
A substance made up of two or more types of atoms chemically combined together.
Compounds can be ionic or covalent in nature.
What does concentration refer to?
The amount of substance (e.g. the mass) in a certain volume of a solution.
Concentration is often expressed in molarity (moles per liter).
Define a conductor.
A material that contains charged particles which are free to move to carry electrical or thermal energy.
Metals are common examples of good conductors.
What is the conservation of mass?
A law which states that no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants.
This principle is fundamental in chemical equations.
What is a covalent bond?
A shared pair of electrons between two non-metals.
Covalent bonds result in the formation of molecules.
Describe the Dalton model.
Dalton described atoms as solid spheres, stating that different spheres made up the different elements.
This model was one of the first to propose a theory of atomic structure.
What is diamond?
A giant covalent structure made up of carbon atoms, each forming four covalent bonds with four other carbon atoms.
Diamond is known for its hardness and is used in cutting tools.
What is an electron?
Negatively charged subatomic particle which orbit the nucleus at various energy levels
Very small relative mass (negligible)
What is an electron shell?
Different energy levels in atoms occupied by electrons
What are electrostatic forces?
The strong forces of attraction between oppositely charged ions
Define an element.
A substance made up of only one type of atom
What is an empirical formula?
The simplest whole number ratio of atoms of each element in a compound