1. Chapter 3 Atoms and the Periodic Table
What are atoms?
Tiny units that determine the properties of all matter
What does atom mean in Greek?
Unable to be divided

2. What is the atomic mass?
The mass of an atom based on the average mass of isotopes of the element
The mass of the protons + the neutrons in the nucleus of the element
example 6 C 12
has an atomic mass of 12

3. What is the atomic number of an atom?
The number of protons in the nucleus
The number of protons gives the atom its identity 6 C
12 Has 6 protons

4. The central portion of an atom, containing both neutrons and protons
What is a nucleus?
The central portion of an atom, containing both neutrons and protons

5. What is a neutron and where is it located?
The neutral particle found in the nucleus of an atom which has a mass about equal to a proton
Determined by subtracting the number of protons from the mass number of the element
Example: 8 O
neutrons= 16-8 =8

6. Positively charged particle in the nucleus of an atom
What is a proton?
Positively charged particle in the nucleus of an atom
Atomic number of an element gives an element its identity
Example 7 N
14 has 7 protons

7. What is an electron and where is it located
The negatively charged particle in the electron cloud of an atom
Equal to the atomic number of a neutral element and the atomic number minus the charge for an elemental ion
Example:
C C+4
12 has has 6-4=2

8. What are valence electrons?
outer most energy
level electrons

9. Information represented for an element8
atomic number (protons) O
element symbol
15.99
atomic mass

10. What is electron affinity?
The attraction of an atom for an additional electron
Metals have low affinity because they give away electrons
Nonmetals have high affinity because they take on electrons
The electron affinity tends to increase from left to right in the periodic table and from bottom to top

11. What are families/groups?
Elements grouped together by common properties. They fall in the same vertical column of the periodic table
Column #1alkali metals (+1 oxidation #)
Column #2 alkaline earth metals(+2 oxid #)
Column #3-12 transition metals (many have multiple oxidation number-least reactive of the metals)
Column #16 chalcogens (-2 oxidation #)
Column #17 halogens (-1 oxidation #) most reactive nonmetals
Column #18 noble gases (0 oxidation #) nonreactive due to filled outer energy level
lanthanide series
actinide series

12. Where is the period in the periodic table?
Horizontal rows in the periodic table
Each represents an energy level

13. What are metals? Groups of elements that has: Luster (shiny)
Good conductors of heat and electricity
1-3 valence electrons
Located in the periodic table left of the metalloids excluding H
Solids are room temperature(ex mercury)

14. Elements that have properties of both metals and nonmetals.
What are metalloids?
Elements that have properties of both metals and nonmetals.
Located diagonally between the metals, nonmetals
B, Si, Ge, As, Sb, Te, At

15. What are nonmetals? Elements that do not have properties of metals
Located on the right side of the periodic table
Have more than 4 valence electrons
Dull/lack luster
Do not conduct heat or electricity well
Typically gases or brittle solids at room temperature

16. What is a subscript?
Small lowered number after the symbol for an element that indicates the number of atoms of the element present in the formula of the molecule
Subscripts of one in a symbol are understood and therefore not shown
Example O2 or NaCl or K2SO4

17. What is ionization energy
Energy needed to remove an electron from an atom.
Ionization energy tends to increase from left to right and decrease from top to bottom

18. Periodic trends of Elements
Reactivity of metals increases down the periodic table and from right to left across the periodic table
Reactivity of non metals increases up the periodic table and from left to right across the periodic table
Atomic radius increases down the periodic table and form right to left across the periodic table