The Atom

1. Matter is made out of elements. 2. An element is a substance that has a characteristic(trait) set of physical and chemical properties.

Over ninety elements occur naturally in the earth Over ninety elements occur naturally in the earth. Another dozen or so have been created in the laboratory. Of the natural elements, only eight make up over 98% of the earth’s crust. In fact, two elements – silicon and oxygen – make up almost 75% of the earth’s crust.

3. Elements consist(made) of atoms. 4. The atom is the smallest particle(piece) of an element that retains(keeps) its identity in that element.

The word atom, comes from a Greek word for “indivisible” The word atom, comes from a Greek word for “indivisible”. You can identify an element by its atoms. Atoms cannot be broken down into smaller particles(pieces), that have the same chemical and physical properties, by ordinary(regular) physical(cut) or chemical(acid) processes.

Check for understanding An element is a) A substance that cannot be made into a simpler form by ordinary processes b) The smallest unit of a chemical unit c) A group of identical atoms d) All of the above

Atomic Structure. Atoms are made up of smaller parts called subatomic particles(parts). Three kinds of subatomic particles are electrons, protons, and neutrons

Electrons are negatively charged subatomic particles Electrons are negatively charged subatomic particles. They are the smallest of the three fundamental(main) particles in an atom

Protons are positively charged subatomic particles.

Neutrons have subatomic particles with no charge but with the mass nearly equal to that of a protons.

The nucleus is a tiny central core of an atom and his compose a protons and neutrons

In the nuclear atom, the protons and neutrons are located in the nucleus. The electrons are distributed around the nucleus and occupy almost all the volume(size) of the atom. Because neutrons do not carry an electrical charge, the protons give the nucleus a positive charge.

Comparing distance Compared with the size of the whole atom, the nucleus takes up about the same space as a gumdrop in a football stadium! The electrons of an atom move in a certain region of space around the nucleus known as an electron cloud. Because opposite electrical charges attract, the negative charge electrons are attracted to the positively charged nucleus.

Explain why the nucleus has a positive charge Activity Explain why the nucleus has a positive charge

Lesson stop Complete the daily activity

Day 2.

Atomic number To help in the identification of elements, scientists have assigned an atomic number to each kind of atom. Elements are different because they contain(have) different numbers of protons.

13. The atomic number of an element is the number of protons in the nucleus of an atom of that element. It also represents the number of electrons in a neutral atom of that element.

How many protons and electrons are in the following elements? 3 Li 6.941 8 O 15.999 5 B 10.81 P= ___ E= ___ P= ___ E= ___ P= ___ E= ___

Mass Number Each atom has a mass number. The total number of protons and neutrons in an atom is called the Mass number or atomic mass.

The number of neutrons in an atom is the difference(-) between the mass number and atomic number. Mass number - atomic number = Neutrons Or Neutrons + protons = mass number

**first round the mass number FIND THE NEUTRONS **first round the mass number Mass number - atomic number = IF neither the atomic number nor atomic mass is provided how can we use a model to find the neutrons?

FIND THE NEUTRONS Mass 12.01 Protons 6 Electrons 6 Neutrons __????__

Isotopes Although all atoms of a given element contain the same number of protons, they do not always contain the same number of neutrons. Remember: Neutrons + Protons = Mass So if more neutrons are added what happens to the mass? What if there were less neutrons?

Atoms of the same element that differ from each other in mass number are called isotopes- PROTONS NEVER CHANGE

Isotopes are atoms that have the same number of protons but different numbers of neutrons.

Questions An element is A substance that cannot be made into a simpler form by ordinary chemical means. The smallest unit of a particular type of chemical. Identical to all atoms of the same element. All of the above

Which of the following particles has a positive electrical charge? Electron Proton Nucleus Neutron

A nucleus contains which particle(s). Neutron, protons and electrons. Proton and electrons. Electrons and neutrons. Protons and neutrons.

Isotopes of an element must have a given number of protons but may have a variety of numbers of neutrons. True False

For an atom to have neutral charge it must have the same number of protons and neutrons. True False

Ticket out the door The atomic number of calcium is 20, and the atomic number of copper is 29. Which has more electrons, a calcium atom or a copper atom? How do you know?