Periodic Table and Periodic Table and Structure of AtomStructure of Atom

Chemistry Honors2014-2015

MAC Dr. Saha

Structure of Atom

https://www.youtube.com/watch?v=lP57gEWcisY&feature=player_embedded

I am Dmitri Mendeleev!I am Dmitri Mendeleev!

I made the PERIODIC TABLE !I made the PERIODIC TABLE !

What is the PERIODIC What is the PERIODIC TABLE?TABLE?

o Shows all known Shows all known elements in the elements in the universe.universe.

o Organizes the Organizes the elements by chemical elements by chemical properties.properties.

How do you read the How do you read the PERIODIC TABLE?PERIODIC TABLE?

What is the ATOMIC NUMBER?What is the ATOMIC NUMBER?

o The number of The number of protons found in protons found in the nucleus of an the nucleus of an atomatom

OrOro The number of The number of

electrons electrons surrounding the surrounding the nucleus of an atom.nucleus of an atom.

What is the SYMBOL?What is the SYMBOL?

o An abbreviation An abbreviation of the element of the element name.name.

What is the ATOMIC WEIGHT?What is the ATOMIC WEIGHT?

o The number of The number of protons and protons and neutrons in the neutrons in the nucleus of an atom.nucleus of an atom.

How do I find the number of How do I find the number of protons, electrons, and neutrons protons, electrons, and neutrons in an element using the periodic in an element using the periodic

table?table?o # of PROTONS# of PROTONS = ATOMIC NUMBER= ATOMIC NUMBER

o # of ELECTRONS# of ELECTRONS = ATOMIC NUMBER= ATOMIC NUMBER

o # of NEUTRONS# of NEUTRONS = ATOMIC _ ATOMIC= ATOMIC _ ATOMIC WEIGHT WEIGHT NUMBERNUMBER

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Elements, Compounds, Elements, Compounds, and Mixturesand Mixtures

What is an ELEMENT?What is an ELEMENT?o A substance A substance

composed of a composed of a single kind of single kind of atom.atom.

o Cannot be broken Cannot be broken down into another down into another substance by substance by chemical or chemical or physical means.physical means.

What is a COMPOUND?What is a COMPOUND?

o A substance in A substance in which two or which two or more different more different elements are elements are CHEMICALLY CHEMICALLY bonded bonded together.together.

What is a MIXTURE?What is a MIXTURE?

o Two or more Two or more substances substances that are mixed that are mixed together but together but are NOT are NOT chemically chemically bonded.bonded.

Element, Compound or Element, Compound or Mixture?Mixture?

Element, Compound or Element, Compound or Mixture?Mixture?

Element, Compound or Element, Compound or Mixture?Mixture?

Element, Compound or Element, Compound or Mixture?Mixture?

Element, Compound or Element, Compound or Mixture?Mixture?

Element, Compound or Element, Compound or Mixture?Mixture?

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https://www.youtube.com/watch?v=UDIprICe9kg

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 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 Isotopes of Some Elements and Their Atomic MassTheir 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: 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of the following:

12C 13C 14C 6 6 6

protons ______ ______ ______

neutrons ______ ______ ______

electrons ______ ______ ______

Isotopes of C

Video showing how to take weighted average

https://www.youtube.com/watch?https://www.youtube.com/watch?v=kKSyHQyJEUMv=kKSyHQyJEUM

35Cl has atomic mass 34.97 amu (75.76%) and 37C has atomic mass 36.97 amu (24.24%).

• Use atomic mass and percent of each isotope to calculate the contribution of each isotope to the weighted average. 34.97 x 75.76 = 26.49 amu 10036.97 x 24.24 = 8.961 amu

100 • Average atomic mass of Cl = 35.45 amu

Calculating Atomic Mass for ClCalculating 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.

+ + +

Hydrogen Deuterium Tritium

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.

https://www.youtube.com/watch?v=TJgc28csgV0

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

HeThU 42

23490

23892

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-222.

226 222 4

Ra → Rn + He

88 86 2

• 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

146 C 14

7 N + 01 e

http://www.glencoe.com/sites/common_assets/science/cmc/cim/animations/ch4_3.swf

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.