Chapter 5- Minerals (Week 3) Flashcards
What is a mineral?
Definition: A mineral is a naturally occurring solid composed of specific elements, arranged in a distinctive repeating three-dimensional structure.
Characteristics:
-Naturally Occurring: Formed from substances and conditions found in nature.
-Solid: Generally solid at 25°C (with exceptions for substances defined as minerals before 1959).
Exclusions: Anthropogenic materials (made only by humans) and substances produced by natural processes acting upon anthropogenic materials are not considered minerals.
Examples: Common minerals include graphite, salt, plaster, gold, and others found in everyday items.
What does “naturally occurring” mean in the context of mineral definition?
In the context of mineral definition, “naturally occurring” indicates that minerals can form from substances and under conditions found in nature. Anthropogenic materials, or substances produced solely by humans, do not qualify as minerals based on this criterion.
What does “specific elements” mean in the context of mineral definition?
In the context of mineral definition, “specific elements” implies that minerals have a well-defined chemical formula or composition. Deviation from this formula would result in a different mineral. For example, the mineral pyrite has the formula FeS2, signifying two atoms of sulfur for each atom of iron.
What is solid solution in the context of minerals?
Solid solution refers to a variation in the composition of a mineral within a specific range. It allows for the substitution of one element for another within the mineral’s structure. An example is the mineral olivine, with the formula (Fe,Mg)2SiO4, allowing a range of compositions between Fe2SiO4 and Mg2SiO4, with any proportion of iron and magnesium in between.
Why are all minerals considered crystals?
All minerals are considered crystals because the atoms within them are arranged in a specific repeating three-dimensional structure or lattice. This regular structure is a defining characteristic of minerals. For instance, the mineral halite, or table salt, exhibits a crystal lattice where atoms of sodium (Na) alternate with atoms of chlorine (Cl), forming a consistent structure. Even small crystals have lattices that extend in three dimensions, repeating thousands of times.
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What is the term for substances that have mineral-like properties but lack a regular crystalline structure?
Substances that have mineral-like properties but lack a regular crystalline structure are called mineraloids. Opal is an example of a mineraloid. While opal has a specific chemical composition (SiO2·nH2O) and forms naturally, its structure consists of closely packed spheres instead of a lattice.
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Can opal be considered a mineral?
Opal is not classified as a mineral but as a mineraloid. While it has mineral-like characteristics, including a specific chemical composition, it lacks the regular crystalline structure typical of minerals. Opal’s structure consists of closely packed spheres, distinguishing it from minerals with crystalline lattices.
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What are the three main particles that make up atoms, and what are their charges?
The three main particles that make up atoms are protons, neutrons, and electrons. Protons have a positive charge, neutrons have no charge, and electrons have a negative charge.
Why is it possible to have more than one proton in an atomic nucleus despite protons having a positive charge that repels each other?
Neutrons, which have no charge, hold protons together in an atomic nucleus, allowing for the presence of multiple protons. While protons repel each other due to their positive charge, neutrons act as a stabilizing force within the nucleus. The combination of protons and neutrons forms the nucleus at the center of an atom
What are isotopes?
Isotopes are forms of an element that have the same number of protons but different numbers of neutrons. They can exist for various elements, resulting in atoms with similar chemical properties but different atomic masses
What determines the element an atom will be, and what is the term for the number of protons in an atom?
The element an atom will be is determined by the number of protons it possesses. This number is called the atomic number.
What is the mass number of an atom, and how does it relate to the atomic number?
The mass number of an atom is the total number of protons and neutrons in its nucleus. It distinguishes between isotopes of an element. While the atomic number (number of protons) defines the element, the mass number provides information about the isotope’s atomic mass.
How are isotopes of an element denoted, and can you provide an example?
Isotopes of an element are denoted by placing the mass number as a subscript in front of the symbol for that element. For example, the isotopes of hydrogen are 1H (1 proton), 2H (1 proton + 1 neutron), and 3H (1 proton + 2 neutrons).
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Why do most of the lightest elements (up to oxygen) have the same number of neutrons as protons in their nuclei?
For most of the 16 lightest elements, the number of neutrons is equal to the number of protons in their nuclei. However, for heavier elements, especially those with more concentrated protons, more neutrons are needed to counteract the repulsion between positively charged protons and keep the nucleus stable.
Why is uranium (U) considered radioactive, and what happens during its radioactive decay?
Uranium is radioactive because its nucleus is unstable and will eventually split apart, a process known as radioactive decay. During decay, the nucleus releases energy, and what remains of the nucleus has fewer protons, leading to a transformation into a different element. The most common isotope of uranium is 238U, with 92 protons and 146 neutrons.
Why are the outermost electrons crucial for chemical bonding, and can you provide an example of an element with incomplete outer shells?
The outermost electrons, or valence electrons, are crucial for chemical bonding as they can interact with the outer electrons of nearby atoms. For example, lithium (Li) is an element with incomplete outer shells, and its outermost electrons can participate in forming chemical bonds with other atoms.
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How many electrons can the first and subsequent electron shells hold, and what is the maximum number of outermost electrons an atom can have for chemical bonding?
The first shell can hold up to two electrons, and subsequent shells can hold up to eight electrons each. There are never more than eight outermost electrons influencing chemical bonding interactions.
What is the significance of a full outer shell for atoms, and how many electrons does the first shell of an atom aim to have?
Atoms seek to have a full outer shell, and for hydrogen and helium, a full outer shell means two electrons. For other elements, it means having 8 electrons in the outer shell
How do atoms achieve a full outer shell, and why is this process significant in the study of minerals?
Atoms achieve a full outer shell by transferring or sharing electrons with other atoms in chemical bonds. This process is significant in the study of minerals because the type of chemical bond influences many physical and chemical properties of minerals.
What determines the type of chemical bond formed between atoms, and why is it crucial in understanding mineral properties?
The type of chemical bond formed between atoms is determined by how electrons are transferred or shared. It is crucial in understanding mineral properties because the type of bond influences various characteristics of minerals.
How many electrons can the first shell of an atom hold, and why is it relevant in the context of chemical bonding?
The first shell of an atom can hold up to two electrons. This is relevant in chemical bonding as the outermost electrons, or valence electrons, determine how atoms bond with each other.
Explain the process of forming an ionic bond with the example of halite (NaCl).
In the example of halite (NaCl), sodium (Na) readily gives up an electron to achieve a full outer shell, becoming a positive ion or cation. Chlorine (Cl) accepts the electron to fill its outer shell, becoming a negative ion or anion. The attraction between these oppositely charged ions creates an ionic bond in NaCl.
What is an ion, and how do ions form in the context of ionic bonds?
An ion is a charged atom that forms when an atom gains or loses electrons. In ionic bonds, atoms transfer electrons, resulting in positively charged ions (cations) and negatively charged ions (anions).
You can remember that a cation is positive by remembering that a cat has paws (paws sounds like “pos” in “positive”). You could also think of the “t” in “cation” as a plus sign.
Why do sodium and chlorine ions stick together in an ionic bond?
Sodium and chlorine ions stick together in an ionic bond due to the attraction between oppositely charged ions. The positive charge of the sodium ion (cation) attracts the negative charge of the chlorine ion (anion).
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What is the role of electrons in the formation of an ionic bond?
In an ionic bond, electrons transfer from one atom to another. This electron transfer results in the formation of positive and negative ions, and the attraction between these ions creates the ionic bond.
Explain how covalent bonds form, using the example of chlorine gas (Cl2) and carbon.
In covalent bonding, atoms share electrons to achieve a full outer shell. In the case of chlorine gas (Cl2), two chlorine atoms share electrons to complete their outer shells. Carbon also participates in covalent bonding by sharing electrons, as seen in the formation of strong covalent bonds in the mineral diamond.
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Why does carbon prefer covalent bonding over ionic bonding?
Carbon prefers covalent bonding over ionic bonding because gaining or losing four electrons to achieve a filled outer shell would create too great a charge imbalance. Covalent bonding allows carbon to share electrons and achieve a stable configuration.
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How are carbon atoms arranged in the mineral diamond, and what type of bonds do they form?
In the mineral diamond, carbon atoms are linked together in a three-dimensional framework. Each carbon atom is bonded to four other carbon atoms through very strong covalent bonds.
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What is the difference between ionic and covalent bonds?
Ionic bonds involve the transfer of electrons between atoms, creating oppositely charged ions that attract each other. Covalent bonds involve the sharing of electrons between atoms to achieve a stable electron configuration.
Describe the bonding in the mineral graphite and explain why it has a soft texture.
In graphite, carbon atoms are covalently bonded within layers, but weak Van der Waals forces hold the layers together. This structure gives graphite its soft texture as the layers can slide over each other easily.
What are Van der Waals forces, and how do they contribute to the properties of materials like graphite?
Van der Waals forces are weak attractive forces between molecules. In graphite, these forces are responsible for holding the layers together. While the covalent bonds within layers are strong, the weak Van der Waals forces between layers allow them to slide easily, giving graphite its unique properties.
Compare the charge distribution in a water molecule to that in a carbon dioxide molecule, and explain how this affects their properties.
In a water molecule, the bent shape causes an asymmetric charge distribution with hydrogen atoms on one side and oxygen on the other, leading to a polar molecule. In carbon dioxide, the linear shape results in a symmetric distribution. The asymmetry in water molecules contributes to properties like hydrogen bonding and high surface tension
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Describe metallic bonding and mention two important properties of metals associated with this type of bonding.
Metallic bonding occurs in metallic elements where outer electrons are relatively loosely held. In this type of bonding, dissociated electrons can move freely between atoms. Two important properties of metals due to metallic bonding are electrical conductivity and malleability.
Why do metals exhibit electrical conductivity and malleability? How does metallic bonding contribute to these properties?
In metallic bonding, dissociated electrons can move freely between atoms. This mobility of electrons allows metals to conduct electricity. Additionally, the ability of atoms to slide past each other while maintaining the metallic bond contributes to the malleability of metals.
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How are minerals organized, and what is the basis for this organization?
Minerals are organized based on the anion or anion group they contain. This is because the anion or anion group has the most significant impact on the properties of the mineral.
Which anion or anion group is the most abundant in the Earth’s crust and mantle?
Silicates, with the anion group SiO44-, are the most abundant group in the Earth’s crust and mantle.
What are some examples of mineral groups, and how are they classified?
Mineral groups are classified based on the anion or anion group they contain. Examples include oxides, sulfides, sulfates, halides, carbonates, phosphates, and silicates.
What is the basis for classifying minerals as oxide minerals?
Oxide minerals are classified based on the oxygen anion (O2–) they contain.
Can you provide examples of oxide minerals and their uses?
Examples of oxide minerals include hematite and magnetite (ores of iron), corundum (used as an abrasive and as a gemstone in ruby and sapphire varieties), limonite, and bauxite (ores of iron and aluminum, respectively).
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What is a hydroxide mineral, and can you provide examples?
A hydroxide mineral is one in which oxygen is combined with hydrogen to form the hydroxyl anion (OH–). Examples include limonite and bauxite, which are ores of iron and aluminum, respectively.
What is the defining feature of sulphide minerals, and can you name some examples?
Sulphide minerals are characterized by the presence of the sulphide anion (S2-). Examples include galena, sphalerite, chalcopyrite, molybdenite (important ores of lead, zinc, copper, and molybdenum, respectively), pyrite, bornite, stibnite, and arsenopyrite.
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What is a common visual characteristic of sulphide minerals?
Sulphide minerals tend to have a metallic sheen.
How do sulphate minerals typically form, and what can a deposit of sulphate minerals indicate about the past environment?
Sulphate minerals often form when sulphate-bearing water evaporates. A deposit of sulphate minerals may indicate that a lake or sea has dried up at that location.
Can you name some sulphate minerals and the cations they contain?
Examples of sulphate minerals include anhydrite and gypsum (calcium sulphates), barite (barium sulphate), and celestite (strontium sulphate). In these minerals, the cation has a +2 charge, balancing the -2 charge on the sulphate ion.
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What are halide minerals, and what are the anions they contain?
Halide minerals are those that contain anions from the halogen group, including chlorine, fluorine, and bromine. Examples include cryolite, fluorite, and halite. Halide minerals are typically formed by ionic bonds, and some may also form when mineral-rich water evaporates.
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Which anion group combines with +2 cations to form minerals such as calcite, magnesite, dolomite, and siderite?
The carbonate anion group (CO3^2-) combines with +2 cations to form minerals such as calcite, magnesite, dolomite, and siderite.
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What is the anion group associated with the apatite group of phosphate minerals?
The phosphate minerals in the apatite group are associated with the PO4^3- anion.
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Can you provide examples of native element minerals?
Examples of native element minerals include gold, copper, silver, and sulfur.
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What is the basic building block of many important minerals in the crust and mantle?
The basic building block of many important minerals in the crust and mantle is the silicate tetrahedron (SiO44-).
a four-sided pyramid shape with oxygen at each corner and silicon in the middle
Silicon has a charge of +4, and oxygen has a charge of -2, so the total charge of the silicate anion is -4.
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