1. What is an Atom?
The smallest part of an element which retains the properties of that element.

2. Atom Nucleus Protons Neutrons Electrons

3. Proton
Positively charged subatomic particle(s) that are found in the nucleus of an atom.

4. Neutron
Neutral, subatomic particle(s) bearing no charge that are found in the nucleus of an atom.

5. Electron
Negatively charged subatomic particle(s) that are found outside of the nucleus of an atom.

6. Subatomic Particles

7. Does an atom have a charge?
NO, matter around us is neutral.
So what can you tell me about the number of protons and electrons in an atom?
Atoms are always neutral therefore protons always equal electrons.

8. The Periodic Table Elements are so periodic !
“Repeats at regular intervals”

9. Dimitri Mendeleev Russian chemist
Published first version of periodic table in 1869
Put elements in order of increasing atomic mass
All elements were not known at that time, but he was able to predict the elements that fit in the gaps.

10. Henry Moseley
Early 20th century improved the table by arranging the elements , by atomic
Number (#protons)
This made it more clear
Which elements were
missing

11. the arrangement of electrons in the energy levels of a Bohr model
How to read it
Atomic
Mass
Symbol
Represents
the name
of the chemical
Represents the
number of
protons and neutrons
in the nucleus 12 C
Atomic
Number
Electron
Configuration
Represents the
number of
protons
in the nucleus
Represents
the arrangement of electrons in the energy levels of a Bohr model 6
2 - 4

12. Do Now Atomic Mass = Atomic number =
If an atom has a mass of 65 and an atomic number of 30 how many protons, neutrons, and electrons does it have?

13. Modern Periodic table arranged into periods 1-7
Horizontal rows of elements
Side to side
Increase in Atomic number from left to right Li Be B C N O F Ne

14. Families of Elements He Ne Vertical columns of elements Ar
Up & Down
Also referred to as Groups
Share common characteristics or properties He Ne Ar Kr Xe Rn

15. Number of protons found in a nucleus, defines an atom
Atomic Number
Number of protons found in a
nucleus, defines an atom

16. Total of protons and neutrons found in the nucleus of an atom
Atomic Mass
Total of protons and neutrons
found in the nucleus of an atom

17. Metals Similar in many properties Luster/Shiny
Malleable (can be pressed into sheets)
Conduct heat and electricity
Ductile (can be drawn out into wires)

18. Nonmetals Usually gases or brittle solids
Most are poor conductors of heat and electricity
Most are gases at room temperature

19. Metalloids Have some properties of both metals and nonmetals
Along the stair step
Ex: boron has luster but is a
Poor conductor of electricity

20. Green – metals
Yellow – nonmetals
Blue - metalloids

21. PERIODIC PATTERNS Li Be B C N O F Ne
Atoms increase in mass from the left side to the right side in each row.

22. More Patterns
Atoms in the same family (group) increase in size from top to bottom.
Ex: Na (sodium) is bigger than H (hydrogen) H Li Na K Rb Cs Fr

23. Chemical Activity Chemical activity decreases from left to right.
Group 1 are very chemically active metals, Group 18 are chemically inactive gases.
They are called Noble gases.