chem lesson 3
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CHEM LESSON 3. ATOMS AND ELEMENTS. DO-NOW. What are the three parts of an atom called?. Atoms and Elements. Each element consists of atoms that differ from the atoms of other elements. An element can be identified by the number of protons in the nucleus. . Atoms and Elements. - PowerPoint PPT PresentationTRANSCRIPT
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CHEM LESSON 3ATOMS AND ELEMENTS
DO-NOW
What are the three parts of an atom called?
Atoms and Elements
Each element consists of atoms that differ from the atoms of other elements.
An element can be identified by the number of protons in the nucleus.
Atoms and Elements
In the nucleus of the atom, the protons and neutrons are held together by a strong force
Atoms and Elements
Every atom of an element as the same number of protons. We call this the atomic number.
For example, every atom of carbon has 6 protons
Atoms and Elements
Atomic Number is the number of protons in the nucleus for each element.
Oxygen’s atomic number is 8, Iron’s atomic number is 26.
Atoms and Elements
The Atomic Mass is the average mass of an atom for that specific element
Example: Oxygen’s atomic mass is 15.99 and Iron’s atomic mass is 55.847
Atoms and Elements
The atomic mass, atomic number, and the chemical symbol are all organized into a square for each element on the periodic table.
Atoms and Elements
Atomic Number Chemical
Symbol Element Atomic Mass
Atoms and Elements
Electrons are found in an electron cloud surrounding the nucleus.
Atoms and Elements
Electrons are arranged on shells. Shells are the different energy levels on which electrons are found
Electron Shells
The inner most shell can only hold 2 Electrons
The second shell can hold 8 Electrons
The third shell can hold 8 Electrons
Periodic Table
The Periodic Table is how scientists have organized all of the elements.
Periods
1st period: 1 shell 2nd period: 2 shells 3rd period: 3 shells 4th period: 4 shells
• Each row is called a “period”
• The elements in each period have the same number of shells
Groups
Group 1: 1 Electron Group 2: 2
Electrons Group 3: 3
Electrons Group 4: 4
Electrons Ect. All the way up
to group 8: 8 electrons.
• Each column is called a “group”• Each element in a group has the same number of valence electrons• Valence electrons are electrons in the outer shell
3, 4, 5, 6, 7
1, 2
8