Periodic Table and Structure of Atom Chemistry Honors MAC Dr. Saha

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I am Dmitri Mendeleev! I made the PERIODIC TABLE !

What is the PERIODIC TABLE? o Shows all known elements in the universe. o Organizes the elements by chemical properties.

How do you read the PERIODIC TABLE?

What is the ATOMIC NUMBER? o The number of protons found in the nucleus of an atom Or o The number of electrons surrounding the nucleus of an atom.

What is the SYMBOL? o An abbreviation of the element name.

What is the ATOMIC WEIGHT? o The number of protons and neutrons in the nucleus of an atom.

How do I find the number of protons, electrons, and neutrons in an element using the periodic table? o # of PROTONS = ATOMIC NUMBER o # of ELECTRONS = ATOMIC NUMBER o # of NEUTRONS = ATOMIC _ ATOMIC WEIGHT NUMBER WEIGHT NUMBER

Now you are almost as smart as I am!

Elements, Compounds, and Mixtures

What is an ELEMENT? o A substance composed of a single kind of atom. o Cannot be broken down into another substance by chemical or physical means.

What is a COMPOUND? o A substance in which two or more different elements are CHEMICALLY bonded together.

What is a MIXTURE? o Two or more substances that are mixed together but are NOT chemically bonded.

Element, Compound or Mixture?

You are still not as smart as the great Mendeleev! I am working this beard! Man, I look Cool!

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The Structure of atom

Atoms are mostly ____. A.positive B.negative C. solid spheres D. empty space

What are the two fundamental subatomic particles found in the nucleus? A.proton and electron B.proton and neutron C.neutron and electron D.neutron and positron

How Atoms Differ Explain the role of atomic number in determining the identity of an atom. Define an isotope. Explain why atomic masses are not whole numbers. Calculate the number of electrons, protons, and neutrons in an atom given its mass number and atomic number.

Isotopes and Mass Number All atoms of a particular element have the same number of protons and electrons but the number of neutrons in the nucleus can differ. Atoms with the same number of protons but different numbers of neutrons are called isotopes.isotopes

Isotopes and Mass Number (cont.) The relative abundance of each isotope is usually constant. Isotopes containing more neutrons have a greater mass. Isotopes have the same chemical behavior.

Isotopes and Mass Number (cont.)

Mass of Atoms One amu is nearly, but not exactly, equal to one proton and one neutron.

Isotopes of Some Elements and Their Atomic Mass Most elements have two or more isotopes that contribute to the atomic mass of that element.

Naturally occurring carbon consists of three isotopes: 12 C, 13 C, and 14 C. State the number of protons, neutrons, and electrons in each of the following: 12 C 13 C 14 C protons ______ ______ ______ neutrons ______ ______ ______ electrons ______ ______ ______ Isotopes of C

Video showing how to take weighted average  kKSyHQyJEUM

35 Cl has atomic mass amu (75.76%) and 37 C has atomic mass amu (24.24%). Use atomic mass and percent of each isotope to calculate the contribution of each isotope to the weighted average x = amu x = amu 100 Average atomic mass of Cl = amu Calculating Atomic Mass for Cl

An unknown element has 19 protons, 19 electrons, and 3 isotopes with 20, 21 and 22 neutrons. What is the element’s atomic number? A.38 B.40 C.19 D.unable to determine

Elements with the same number of protons and differing numbers of neutrons are known as what? A.isotopes B.radioactive C.abundant D.ions

What are Isotopes?   They are variations of atomic structure for a single element. Atoms that differ only in the number of neutrons in the nucleus are called isotopes HydrogenDeuteriumTritium

Stable and Unstable Isotopes + + Tritium is unstable: breaks down or decays + + Deuterium is stable: does not decay (Stable Isotope) +

Unstable Nuclei and Radioactive Decay Objectives Explain the relationship between unstable nuclei and radioactive decay. Characterize alpha, beta, and gamma radiation in terms of mass and charge.

Section 4.4 Unstable Nuclei and Radioactive Decay (cont.) radioactivity nuclear reaction radioactive decay half-life alpha radiation Unstable atoms emit radiation to gain stability. alpha partices beta radiation beta particles gamma rays

Unstable nuclei Atoms that contain too many or two few neutrons are unstable and lose energy and particles to form a stable nucleus.

Radioactivity and Radiation Unstable atomic nuclei will spontaneously decompose or break down to form nuclei with a higher stability. The decomposition process is called radioactivity. The energy and particles which are released during the decomposition of unstable nuclei are called radiation.

Radioactive Decay Radioactive decay is the conversion of unstable nuclei of radioactive element to stable isotope of the same element or to a completely different element. gc28csgV0

A reaction that changes one element into another element or to an isotope of the same element is called what? A.chemical reaction B.beta radiation C.nuclear reaction D.physical reaction

Nuclear Equation

Half-life The time required for number of unstable atoms to decrease by half.

Radioactive decay of a hypothetical isotope with a half-life of one day. The sample decays each day by one- half.

Types of Radiation: Alpha Alpha radiation is made up of positively charged particles called alpha particles Each alpha particle contains two protons and two neutrons and has a 2 + charge.

Types of Radiation: Alpha The equation shown below is an equation showing the radioactive decay of radium-226 to radon Ra → Rn + He

Beta radiation is radiation that has a negative charge and emits beta particles. Each beta particle is an electron with a 1– charge. Types of Radiation: Beta

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Radioactive Decay (cont.) Gamma rays are high-energy radiation with no mass and are neutral. Gamma rays account for most of the energy lost during radioactive decay.

A reaction that changes one element into another element or to an isotope of the same element is called what? A.chemical reaction B.beta radiation C.nuclear reaction D.physical reaction

Why are radioactive elements rare in nature? A.They do no occur on Earth. B.Most have already decayed to a stable form. C.They take a long time to form. D.They are too hard to detect.