CH 115 1st Edition Lecture 2Unit 1: Atoms, Isotopes and IonsOutline of Last Lecture I. Introductiona. What is Chemistry and Why it MattersII. Types of Matter and Chemical Symbolisma. Definition of Matteri. Definition of elements, compounds, atoms and moleculesii. Atomic Theoryb. Chemical SymbolismIII. The Periodic Tablea. Basic Informationb. Different Categories of Elementsc. Breakdown of Important Groups and PeriodsOutline of Current Lecture IV. Atomsa. Subatomic particlesb. Mass and Volume of Atomsc. Atomic Number and Mass NumberV. Isotopesa. Atomic Weightb. Percent AbundanceCurrent LectureAtomsThe smallest particle of an element that embodies the chemical properties of that element.- Atoms are primarily composed of 3 subatomic particles:o Proton – Has a positive charge. Its mass is 1.672621637 × 10 ‐ 24 g. The number of protons determines the element (i.e. Oxygen is the only element with 8 protons). 2nd most massive of the 3 subatomic particles.o Neutron – Has a neutral charge. Its mass is 1.674927211 × 10 ‐ 24 g. Neutrons are found in the nucleus with protons. Most massive of the 3 subatomic particles.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Electron – Has a negative charge. Its mass is9.10938215 × 10 ‐ 28 g. Electrons arefound in various orbitals outside of the nucleus. Least massive of the subatomic particles.- Protons and neutrons are nearly 2000 timesmore massive than electrons.- Typically, the number of protons equals the number of electrons.- The nearest electron in an atom is fairly far away, meaning that atoms are mostly just empty space)- Nucleus – the totalnumber of protons and neutrons. The nucleus accounts for most of the atom’s mass and is very compact. - Atomic Number– Represents the number of PROTONS. Atomic number is often represented by the letter Z- Mass Number – the number of protons and neutrons. - Mass numbers approximate the atoms- An element with a particular mass number iswritten as “mass numberSymbol” Isotopes- Isotopes– atoms with the same atomic numberbut different mass numbers. The mass number varies due to a difference in neutrons. (examples are 35Cl and 37Cl)- Isotopic mass– the mass of a particular isotopeof an element (in atomic mass units)- Atomic Mass Units (AMU) – a more simple way of expressing weight.- Percent abundance– the percentage of anelement that comes from a particular isotope.- Atomic weight – the weighted average of theisotopic masses of an