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Course: AP®︎/College Biology > Unit 1. Lesson 2: Elements of life. Elements and atoms. Matter, elements, and atoms. Carbon as a building block of life. Carbon and hydrocarbons. Functional groups.
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Learn about atoms, elements, and the periodic table with Khan Academy's comprehensive resources.
Introduction to the atom (video) | Khan Academy
Learn how atoms are made up of protons, neutrons, and electrons. Elements are defined by the atomic number, the number of protons in the nucleus. The mass of an atom is determined by the total number of protons and neutrons.
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Learn about protons, neutrons, and electrons in atoms from Khan Academy.
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When forming ions, elements typically gain or lose the minimum number of electrons necessary to achieve a full octet. For example, fluorine has seven valence electrons, so it is most likely to gain one electron to form an ion with a 1- charge.
Periodic Table - Khan Academy
Unit 1: Atoms, compounds, and ions. Introduction to the atom: Atoms, compounds, and ions History of atomic structure: Atoms, compounds, and ions Bohr's model of the hydrogen atom: Atoms, compounds, and ions Quantum numbers and orbitals: Atoms, compounds, and ions Electron configurations: Atoms, compounds, and ions.
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Electron configurations describe where electrons are located around the nucleus of an atom. For example, the electron configuration of lithium, 1s²2s¹, tells us that lithium has two electrons in the 1s subshell and one electron in the 2s subshell.
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The periodic table organizes elements into groups and periods based on their chemical and physical properties. Elements in the same group share similar characteristics, like reactivity. The table is divided into metals, nonmetals, and metalloids, each with distinct properties.
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Learn about the Bohr model and atomic spectra with free educational resources on Khan Academy.