Examples- #1: The nucleus of an atom contains protons and neutrons. #2: An atom is the smallest unit of matter. #3: An atom is the fundamental building block of matter. This means that it is the smallest particle that keeps the properties of a chemical element and cannot be further broken down chemically.

Website: https://www.britannica.com/science/atom

Examples- #1: The atomic number of any element on the periodic table represents the number of protons in an atom of that element. #2: Hydrogen has a single proton in its nucleus, making its atomic number 1. #3: Helium has two protons in its nucleus, giving it an atomic number of 2. #4: Carbon has six protons in its nucleus, giving it an atomic number of 6. 

Website: https://chem.libretexts.org/Courses/University_of_Arkansas_Little_Rock/Chem_1402%3A_General_Chemistry_1_(Kattoum)/Text/2%3A_Atoms%2C_Molecules%2C_and_Ions/2.02%3A_Atomic_Number%2C_Mass_Number%2C_and_Atomic_Mass_Unit

Examples- #1: Electrons carry a negative electrical charge. #2: They are fundamental particles that make up an atom, alongside protons and neutrons. #3: Electrons are located in shells around the nucleus of an atom.  

Website: https://www.britannica.com/science/electron

Examples- #1: The dots represent the valence electrons of an atom, which are the electrons in the outermost shell and participate in chemical bonding. #2: In the diagram, Nitrogen has five dots, which shows that it has five valence electrons. #3: In the diagram, Carbon has four dots, showing that it has four valence electrons.

Website: https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK12)/08%3A_Ionic_and_Metallic_Bonding/8.01%3A_Electron_Dot_Diagrams

Examples- #1: Examples of elements are hydrogen, oxygen, carbon, sodium, chlorine, nitrogen, calcium, potassium, aluminum, iron, gold, and copper. Elements are any substance that cannot be broken down further into other substances and is made up of only one type of atom. #2: All known elements are listed on the periodic table. #3: Examples of elements in our life is the oxygen we breathe, carbon in our bodies, sodium in salt, and copper in electrical wires. 

Website: https://www.chemicool.com/definition/element.html#google_vignette

Examples- #1: The different energy levels of electrons within an atom are represented by shells like the first energy level, second energy level, and more. #2: Electrons in an atom can only occupy specific energy levels, which are often shown as shells around the nucleus. The closer an electron is to the nucleus, the lower its energy level. #3: An atom is most stable if its outermost energy level contains as many electrons as it can hold.

Website: https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/05%3A_Electrons_in_Atoms/5.12%3A_Energy_Level

Examples- #1: Positively charged ions are called cations. #2: Negatively charged ions are called anions. #3: An ion is an atom or molecule that has gained or lost electrons, resulting in a net electrical charge. 

Website: https://www.britannica.com/science/ion-physics

Examples- #1: Isotopes of an element have the same number of protons (atomic number) but a different number of neutrons which leads to a different atomic mass. #2: The most common example of isotopes is hydrogen, which has three isotopes. protium (hydrogen-1), deuterium (hydrogen-2), and tritium (hydrogen-3). 

Website: https://www.energy.gov/science/doe-explainsisotopes

Examples- #1: Carbon-12. A carbon atom with 6 protons and 6 neutrons has a mass number of 12. #2: Oxygen-16. An oxygen atom with 8 protons and 8 neutrons has a mass number of 16. #3: Chlorine-35. A chlorine atom with 17 protons and 18 neutrons has a mass number of 35. 

Website: https://chem.libretexts.org/Courses/University_of_Arkansas_Little_Rock/Chem_1402%3A_General_Chemistry_1_(Kattoum)/Text/2%3A_Atoms%2C_Molecules%2C_and_Ions/2.02%3A_Atomic_Number%2C_Mass_Number%2C_and_Atomic_Mass_Unit

Example- #1: The number of neutrons in an atom determines its isotope. #2: They are found in the nucleus of an atom alongside protons. #3: They are neutral particles which means that they have no electrical charge. 

Website: https://www.britannica.com/science/neutron

Examples- #1: The nucleus is like the brain of the cell. It controls its functions and contains the chromosomes with genetic information. #2: Animal or plant cells contain a nucleus which contains its genetic material. #3: The nucleus contains all of our genetic information.

Website: https://www.thoughtco.com/definition-of-nucleus-605434

Examples- #1: The periodic table refers to the organized chart that lists all known chemical elements. #2: Each element is identified by its atomic number, which represents the number of protons in its nucleus. #3: The periodic table includes halogens, metals, and gases, but not all elements are classified as one of these categories.

Website: https://www.britannica.com/science/periodic-table

Examples- #1: The number of protons in an atom determines what element it is. #2: Proton counts in different elements are, hydrogen: 1 proton, helium: 2 protons, lithium: 3 protons, carbon: 6 protons, and carbon: 8 protons. #3: Protons carry a positive electrical charge. 

Website: https://www.britannica.com/science/proton-subatomic-particle

Examples- #1: Radioactive atoms have unstable nuclei which decay over time. This releases radiation in the process. #2: Different radioactive elements emit different types of radiation, including alpha, beta, and gamma rays. 

Website: https://www.britannica.com/science/radioactivity

Examples- #1: Oxygen has six valence electrons in its outer shell, allowing it to form covalent bonds with other atoms. #2: When studying chemical reactions, it's very important to understand the distribution of valence electrons in an atom. #3: The reactivity of an element is mostly determined by the number of valence electrons it has.

Website: https://chem.libretexts.org/Courses/Williams_School/Advanced_Chemistry/03%3A_Chemical_Bonding/3.01%3A_Valence_Electrons