Atomic Structure and Isotopes PDF

 Atoms are not indivisible and are made up of three subatomic particles— the protons, the electrons, and the neutrons. The nuclear atom  Location Relative mass Subatomic Relative in th...

 Atoms are not indivisible and are made up of three subatomic particles— the protons, the electrons, and the neutrons. The nuclear atom  Location Relative mass Subatomic Relative in the Symbol (in atomic mass particle charge atom unit) proton p +1 1 inside the nucleus neutron n 0 1 outside the 1 electron e -1 nucleus 1840  Atoms in their neutral state have a zero charge due to the equal number of protons and electrons. The electrons are responsible for almost all chemical properties and reactivities of substances. The nucleus, which contains the protons and the neutrons, are unchanged in chemical reactions but change in energy-driven nuclear reactions. The letters designate the chemical symbol for the element. The number in the upper portion is the element’s atomic number. The number at the lower portion is its mass number. Zinc (Zn), for example, has an atomic number of 30 and an atomic mass of 65.38 amu. In some cases, only the mass number is shown. This notation is also read as zinc-65, or Zn-65. In representing elements using this notation, it is easy to remember that mass numbers are always greater than atomic numbers. Hence, your chemical representation is correct if the left superscript is greater than the left subscript.  The atomic number (Z), also referred to in most references as the proton number (p), represents the total number of protons present in an element. In a neutral atom, the number of protons is equal to the number of electrons. The atomic number does not change during chemical reactions. The atomic number is the soul of the atom. It’s what makes elements itself.  The number of neutrons, however, changes much easier compared to the number of protons. Neutrons serve as buffers between protons in the nucleus. Elements that differ only by a neutron number have the same atomic number, and therefore, have the same chemical identity. This set of elements are referred to as isotopes. The mass number (A), also referred in most references as atomic mass, is defined as the sum of the number of protons (p) and the number of neutrons (n) in an atom. Alternatively, the equation can be rewritten using the element’s atomic number.  The number of neutrons in an atom can also be calculated by taking the difference between the mass number and the atomic number.  Number Number Number Atomic Mass of of of Element Symbol number number protons electrons neutrons (Z) (A) (p) (e) (n) helium lithium berylliu m boron carbon  The electrons, being the tiniest and most mobile of all subatomic particles, can easily be removed out of an atom or captured from an external source. When electrons are removed or captured in an atom, it becomes charged and is transformed to an ion. Charges result when there is an imbalance between the number of electrons and the number of protons.  Since electrons are negatively charged, the removal of electrons produces positively charged ions called cation. Cations have more protons than electrons. Atoms that gain electrons from external sources become negatively charged ions called anions. Anions have more electrons than protons.  The charge number (q) is determined as the difference between the number of protons and the number of electrons. The general notation for any neutral element, where X is its chemical symbol, A is its mass number, and Z is its atomic number. When does the charge number become positive? When does the charge number become negative? Step 1: Identify what is required in the problem. You are asked to determine the number of protons, neutrons, and electrons in a bromine atom. Step 2: Identify the given in the problem. The atomic number and the mass number are given in the nuclear symbol. Step 3: Write the working equations. Step 4: Substitute the given values. Step 5: Find the answer. has 35 protons, 35 electrons, and 44 neutrons. has 13 protons, 13 electrons, and 14 neutrons. has 86 protons, 86 electrons, and 136 neutrons. has 27 protons, 23 electrons, and 32 neutrons.  Concept Formula Description Atomic Mass Use this formula to solve for atomic mass where: if atomic number and A is atomic mass neutron number are Z is atomic number given. n is neutron number  Concept Formula Description Charge Number Use this formula to solve the charge where: number if proton and q is charge number electron numbers are p is proton number given. e is electron number Atoms of the same element that have the same number of protons and electrons but different numbers of neutrons are called isotopes. Most isotopes are naturally occurring.  Artificial isotopes, also known as radioisotopes, can be produced from heavier elements. These isotopes are highly unstable such that when they decay, they release enormous amounts of radioactivity which can be harnessed to power up large scale processes in nuclear reactors. Most radioisotopes are useful in radioactive dating, while some are useful in the detection of tumors and diseases. Isotope Applications americium-241 smoke detectors californium-252 detection of explosives iodine-131 treatment of thyroid diseases carbon-14 age estimation of organic compounds uranium-238 estimation of age of rocks How are radioisotopes produced?  In chemical reactions, only the electrons are involved. Since isotopes have the same number of electrons, they have similar chemical properties. For example, the two isotopes of chlorine—chlorine-35 and chlorine-37—both react with sodium to form sodium chloride. Isotones are elements that have the same number of neutrons. Isobars are elements that have the same mass number but different atomic numbers. Isotopes are sets of elements which have the same number of protons. Isotones are sets of elements which have the same number of neutrons. It follows that isobars are sets of elements which have the same mass numbers. Isotopes are sets of elements which have the same number of protons. Isotones are sets of elements which have the same number of neutrons. It follows that isobars are sets of elements which have the same mass numbers. 1. How do we determine the atomic number and mass number of an element? 2. When does the charge number become positive? When does the charge number become negative? 3. What are isotopes and how do properties of isotopic elements differ from one another? 1. 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