2.3 Atomic Structure and Symbolism
3 min read•june 24, 2024
Atoms are the building blocks of matter, and understanding their structure is crucial. provide a shorthand way to represent atoms, including information about their , , and charge. These symbols are essential for communicating atomic information efficiently in chemistry.
Atomic mass units () allow us to express and compare the masses of atoms and molecules. The concept of takes into account the natural abundance of different , providing a practical way to represent the mass of an element as it occurs in nature.
Atomic Structure and Symbolism
Chemical symbols for atoms
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- Represent atoms using one or two letters ( for , for )
- First letter always capitalized, second letter lowercase if present
- Include () as subscript on left side of symbol
- Indicates number of protons in atom's (), unique for each element
- Include () as superscript on left side of symbol
- Represents sum of protons and neutrons in atom's nucleus
- Indicate as superscript on right side of symbol
- Net charge acquired when atom gains or loses
- Positive charge shown with + sign, negative charge with - sign (²⁺, ⁻)
- Magnitude of charge indicated by number before sign (³⁺)
- Example: represents a atom with 11 protons, mass number of 23, and ionic charge of +1
Atomic mass unit concept
- Expresses atomic and molecular masses using (amu)
- Defined as 1/12 the mass of a atom
- Average atomic mass is weighted average of masses of all naturally occurring
- Takes into account relative abundance of each isotope
- Expressed in amu
- Average atomic mass calculated by summing products of each isotope's mass and fractional abundance
Calculation of average atomic mass
- Formula:
- Example: has two isotopes, (75.77%) and (24.23%)
- Multiply mass of each isotope by its fractional abundance
- :
- :
- Sum the products to obtain average atomic mass
- Multiply mass of each isotope by its fractional abundance
- Determine isotopic abundance when given average atomic mass and individual isotope masses
- Example: has two isotopes, and , with an average atomic mass of 10.81 amu
- Let be the fractional abundance of
- Set up equation:
- Solve for to find fractional abundance of each isotope
- Example: has two isotopes, and , with an average atomic mass of 10.81 amu
Electron Structure and Configuration
- Electrons are arranged in energy levels (also called shells) around the nucleus
- Each contains orbitals, which are regions of space where electrons are likely to be found
- describes the arrangement of electrons in an atom's orbitals
- Follows the Aufbau principle, Pauli exclusion principle, and Hund's rule
- are the electrons in the outermost energy level
- Determine chemical properties and bonding behavior of atoms
Subatomic Particles
- Protons: positively charged particles found in the nucleus
- Neutrons: neutral particles found in the nucleus
- Electrons: negatively charged particles that orbit the nucleus in energy levels and orbitals
Key Terms to Review (46)
Adhesive forces: Adhesive forces are the attractive interactions between unlike molecules. These forces are responsible for phenomena such as capillary action and the spreading of liquids on solid surfaces.
Amu: Atomic mass unit (amu) is a unit of mass used to express the masses of atoms and molecules. It is a fundamental unit in the study of atomic structure and the mole concept in chemistry.
Anion: An anion is a negatively charged ion formed when an atom gains one or more electrons. Anions are typically larger than their parent atoms due to the added electrons.
Atomic Mass Unit: The atomic mass unit (amu) is a unit of mass used to express the masses of atoms and molecules. It is defined as one-twelfth the mass of a carbon-12 atom in its ground state, which is a widely accepted standard for atomic and molecular masses.
Atomic Number: The atomic number is a fundamental property of an element that represents the number of protons in the nucleus of an atom. It is a unique identifier for each element and is a crucial concept in understanding the structure and behavior of atoms, as well as their placement in the periodic table.
Atomic number (Z): The atomic number (Z) is the number of protons found in the nucleus of an atom. It determines the element's identity and its position on the periodic table.
Average Atomic Mass: The average atomic mass, also known as the average atomic weight, is the weighted average of the masses of the naturally occurring isotopes of a chemical element. It represents the typical mass of an atom of that element, taking into account the relative abundance of its isotopes.
B: B is a fundamental concept that spans multiple topics in chemistry, including atomic structure, acid-base chemistry, and the relative strengths of acids and bases. It is a versatile and essential term that underpins our understanding of various chemical phenomena.
Boron: Boron is a metalloid element that is found in the periodic table, with the atomic number 5. It is a hard, brittle, and dark-colored element that is known for its unique properties and applications in various fields, including chemistry, physics, and materials science.
Ca: Ca, or calcium, is a chemical element that is essential for the structure and function of the human body. It is the fifth most abundant element in the Earth's crust and plays a crucial role in a variety of physiological processes, including bone and tooth formation, muscle contraction, nerve function, and blood clotting.
Calcium: Calcium is a chemical element with the symbol Ca and atomic number 20. It is an essential mineral that plays a crucial role in the structure and function of the human body, particularly in the development and maintenance of bones and teeth, as well as in various physiological processes.
Carbon-12: Carbon-12 is the most abundant isotope of the element carbon, with a nucleus containing 6 protons and 6 neutrons. It is the primary standard used to define the atomic mass scale and is a crucial component in understanding atomic structure and the mole concept in chemistry.
Chemical Symbols: Chemical symbols are the one- or two-letter abbreviations used to represent the elements on the periodic table. They serve as a concise way to denote the identity and composition of chemical substances in various contexts, from early atomic theory to writing and balancing chemical equations.
Chlorine: Chlorine is a highly reactive, greenish-yellow gas that is one of the five halogens in the periodic table. It is an essential element in many chemical processes and compounds, with wide-ranging applications in various industries and everyday life.
Cl: Cl is the chemical symbol for the element chlorine, which is a highly reactive halogen gas that is essential for many chemical processes and biological functions in living organisms.
Core electrons: Core electrons are the electrons in an atom that are not involved in chemical bonding. They reside in the inner shells of an atom, closer to the nucleus.
Dalton (Da): A dalton (Da) is a unit of mass used to express atomic and molecular weights. One dalton is approximately equal to the mass of a hydrogen atom, which is about 1/12th the mass of a carbon-12 atom.
Electron configuration: Electron configuration describes the distribution of electrons in an atom's orbitals. It follows principles such as the Aufbau principle, Pauli exclusion principle, and Hund's rule.
Electron Configuration: Electron configuration is the arrangement of electrons in an atom's electron shells and subshells, which determines the atom's chemical properties and behavior. This concept is fundamental to understanding the periodic table, periodic trends, and the reactivity of elements.
Electrons: Electrons are negatively charged subatomic particles that are found in the atoms of all elements. They are responsible for many of the chemical and physical properties of matter, including the formation of chemical bonds and the flow of electrical current.
Energy Level: An energy level is a discrete value of energy that an electron can occupy within an atom. These energy levels are quantized, meaning they can only take on specific, distinct values rather than a continuous range of values. The arrangement and occupation of these energy levels by electrons is a fundamental aspect of atomic structure and determines the chemical properties and behavior of atoms.
Fe: Fe is the chemical symbol for the element iron, which is a transition metal that is essential for various biological processes in the human body. It plays a crucial role in the structure and function of many proteins and enzymes, particularly those involved in oxygen transport, energy production, and cellular respiration.
Fundamental unit of charge (e): The fundamental unit of charge (e) is the smallest unit of electric charge that is considered indivisible in chemistry and physics, quantified as approximately $1.602 \times 10^{-19}$ coulombs. It represents the charge of a single proton or the negative of the charge of a single electron.
H: H is the chemical symbol for hydrogen, the lightest and most abundant element in the universe. It is a key component in many chemical processes and plays a crucial role in various topics in chemistry, including atomic structure, formula mass, and determining empirical and molecular formulas.
He: He, also known as helium, is the second lightest and second most abundant element in the observable universe. It is a colorless, odorless, and inert gas that is widely used in various applications due to its unique properties.
Helium: Helium is a colorless, odorless, and inert noble gas that is the second lightest and second most abundant element in the universe. It is a crucial element in various scientific and industrial applications, with its unique properties making it indispensable in fields ranging from cryogenics to medical imaging.
Hydrogen: Hydrogen is the simplest and lightest element in the periodic table, with a single proton and electron in its neutral state. It is a highly reactive nonmetal that plays a crucial role in various chemical processes and is a fundamental component of many compounds, making it a key topic across several areas of chemistry.
Hydrogen bonding: Hydrogen bonding is a strong type of dipole-dipole interaction that occurs between molecules when hydrogen is covalently bonded to electronegative atoms like oxygen, nitrogen, or fluorine. This bond results in higher boiling and melting points for substances.
Ion: An ion is an atom or molecule that has gained or lost one or more electrons, resulting in a net electric charge. Ions can be either positively charged (cations) or negatively charged (anions).
Ionic Charge: Ionic charge refers to the electrical charge possessed by an ion, which is an atom or molecule that has gained or lost one or more electrons. The ionic charge determines the chemical properties and reactivity of the ion.
Iron: Iron is a chemical element that is essential for many vital processes in the human body. It is a transition metal that plays a crucial role in various topics in chemistry, including atomic structure, the periodic table, chemical nomenclature, corrosion, periodicity, and the occurrence, preparation, and properties of transition metals and their compounds.
Isotopes: Isotopes are variants of a particular chemical element that have the same number of protons but different numbers of neutrons. This results in different atomic masses for the isotopes of an element.
Isotopes: Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons in their nuclei. This difference in the number of neutrons results in variations in the atomic mass of the isotopes, while their chemical properties remain largely the same.
Mass Number: The mass number, also known as the nucleon number, is the total number of protons and neutrons in the nucleus of an atom. It is a fundamental property that helps identify the specific isotope of an element and is denoted by the symbol 'A'.
Mass number (A): Mass number (A) is the total number of protons and neutrons in an atomic nucleus. It determines the mass of an atom.
Na: Na is the chemical symbol for the element sodium, which is a soft, silvery-white alkali metal that is highly reactive and essential for various physiological processes in the human body.
Neutrons: Neutrons are electrically neutral subatomic particles that, along with protons, make up the nucleus of an atom. They are fundamental components of all atomic nuclei, except for the simplest element, hydrogen, which has no neutrons in its nucleus.
Nucleus: The nucleus is the small, dense region at the center of an atom that contains protons and neutrons. It is responsible for most of the atom's mass.
Nucleus: The nucleus is the central and most important part of an atom, containing protons and neutrons, which determines the atom's chemical properties and behavior. It is a critical component in understanding the evolution of atomic theory, atomic structure, the Bohr model, covalent bonding, and nuclear stability and structure.
Orbital: An orbital is a mathematical function that describes the wave-like behavior of an electron in an atom. It defines the probability distribution of an electron's position and energy within an atom. Orbitals are a fundamental concept in understanding the electronic structure of atoms, as they determine how electrons are arranged and behave within the atom.
Protons: Protons are fundamental subatomic particles that make up the nucleus of an atom, carrying a positive electric charge. They are a crucial component in understanding the structure and properties of atoms, which are the building blocks of all matter in the universe.
Sodium: Sodium is a soft, silvery-white, highly reactive alkali metal that is essential for various physiological processes in the human body. It is a key element in the context of atomic structure, the periodic table, chemical nomenclature, formula mass, periodic variations in element properties, and periodicity.
Subatomic Particles: Subatomic particles are the fundamental building blocks that make up atoms and other nuclear structures. These particles are smaller than an atom and include protons, neutrons, and electrons, as well as other more exotic particles like quarks and leptons. Understanding the nature and behavior of subatomic particles is crucial for comprehending the structure and properties of matter at the most fundamental level.
Unified atomic mass unit (u): The unified atomic mass unit (u) is a standard unit of mass that quantifies the mass of atoms and molecules. It is defined as one twelfth the mass of a carbon-12 atom.
Valence electrons: Valence electrons are the outermost electrons of an atom and are involved in forming chemical bonds. They determine an element's chemical properties and reactivity.
Valence Electrons: Valence electrons are the outermost electrons in an atom that participate in chemical reactions and bonding. They are the electrons in the highest occupied energy level of an atom and are responsible for an element's chemical properties and behavior.