Definitions For Topic 1 Key Concepts In Chemistry⬆️ Flashcards

1
Q

What is an anion?

A

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.

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2
Q

Define an atom.

A

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.

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3
Q

What is the atomic nucleus?

A

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.

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4
Q

What does atomic number indicate?

A

The number of protons in the nucleus.

The atomic number uniquely identifies an element.

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5
Q

What is Avogadro’s constant?

A

The number of atoms, molecules, or ions in a mole of a given substance.

Avogadro’s constant is approximately 6.022 x 10^23.

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6
Q

Define a cation.

A

A positively charged ion formed when an atom loses at least one electron.

Cations are typically formed from metals in chemical reactions.

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7
Q

What is a compound?

A

A substance made up of two or more types of atoms chemically combined together.

Compounds can be ionic or covalent in nature.

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8
Q

What does concentration refer to?

A

The amount of substance (e.g. the mass) in a certain volume of a solution.

Concentration is often expressed in molarity (moles per liter).

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9
Q

Define a conductor.

A

A material that contains charged particles which are free to move to carry electrical or thermal energy.

Metals are common examples of good conductors.

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10
Q

What is the conservation of mass?

A

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.

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11
Q

What is a covalent bond?

A

A shared pair of electrons between two non-metals.

Covalent bonds result in the formation of molecules.

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12
Q

Describe the Dalton model.

A

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.

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13
Q

What is diamond?

A

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.

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14
Q

What is an electron?

A

Negatively charged subatomic particle which orbit the nucleus at various energy levels

Very small relative mass (negligible)

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15
Q

What is an electron shell?

A

Different energy levels in atoms occupied by electrons

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16
Q

What are electrostatic forces?

A

The strong forces of attraction between oppositely charged ions

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17
Q

Define an element.

A

A substance made up of only one type of atom

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18
Q

What is an empirical formula?

A

The simplest whole number ratio of atoms of each element in a compound

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19
Q

What are fullerenes?

A

Molecules of carbon atoms with hollow shapes, based on hexagonal rings

Examples include graphene and C60

20
Q

What is a giant covalent molecule?

A

Molecules containing many atoms covalently bonded together

21
Q

What is graphene?

A

A single layer of graphite with properties that make it useful in electronics and composites

22
Q

Describe graphite.

A

A giant covalent structure made up of carbon atoms forming layers of hexagonal rings

23
Q

What is a group in the periodic table?

A

A column of the periodic table where elements have similar chemical properties

24
Q

What are intermolecular forces?

A

The forces which exist between molecules that impact physical properties like boiling/melting point

25
Q

What is an ion?

A

An atom or molecule with an electric charge due to the loss or gain of electrons

26
Q

What is an ionic bond?

A

The bond formed between oppositely charged ions when a metal atom loses electrons and a non-metal gains them

27
Q

Define an ionic compound.

A

Chemical compound formed of oppositely charged ions, held together by strong electrostatic forces

28
Q

What is an isotope?

A

Atoms of the same element with the same number of protons but a different number of neutrons

29
Q

What is a lattice?

A

A repeating regular arrangement of atoms/ions/molecules occurring in crystal structures

30
Q

What is a limiting reactant?

A

The reactant that is completely used up since it limits the amount of products formed.

31
Q

Define mass number.

A

The total number of protons and neutrons in the nucleus.

32
Q

What is a metallic bond?

A

The bonds present in metals between the positive metal ions and negatively charged electrons.

33
Q

What are metals?

A

Elements that react to form positive ions. Found to the left and towards the bottom of the periodic table.

34
Q

What is the unit for amount of substance?

A

Mole. The symbol for the unit mole is mol.

35
Q

What is a molecular formula?

A

The actual ratio of atoms of each element present in a compound.

36
Q

Define a molecule.

A

A group of at least two atoms held together by covalent bonds.

37
Q

What is a neutron?

A

Neutral subatomic particle present in the nucleus of the atom. Relative mass of 1.

38
Q

What are non-metals?

A

Elements that react to form negative ions. Found towards the right and top of the periodic table.

39
Q

What is a period in the periodic table?

A

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

40
Q

What is the periodic table?

A

Table of elements arranged in order of increasing atomic number and such that elements with similar properties are in the same column (group).

41
Q

Define polymers.

A

Large long-chain molecules made up of lots of small monomers joined together by covalent bonds.

42
Q

What is a proton?

A

Positively charged subatomic particle present in the nucleus of the atom. Relative mass of 1.

43
Q

What is relative atomic mass?

A

An average value that takes into account the abundances of the isotopes of the element.

44
Q

Define relative formula mass.

A

The sum of the relative atomic masses of the atoms in the numbers shown in the formula.

45
Q

What are simple molecules?

A

Molecules containing a fixed number of atoms covalently bonded together.

46
Q

What are subatomic particles?

A

Particles smaller than an atom. Protons, neutrons and electrons are the three most common subatomic particles.