Unit 4

Question 1

Three types of elements

Answer 1

metals
non-metals
metaloids

Question 2

metals and properties

Answer 2

• lusterous (shiny)
• hard
• high density
• good conductors of electrisity and heat
• all basically solid
• high melting point
• maluable (move without breaking)
• ductile (stretch into wire)
• all or periodic table under the stairs

Question 3

non-metals

Answer 3

• not lusterous (shiny)
• brittle
• low density
• bad conductor of eletricity and heat
• low melting point
• not maluable and not ductile
• all periodic table above stairs

Question 4

metaloids (semi-metals)

Answer 4

• has properties of both metals and non-metals
• on the stairs

Question 5

Group names

Answer 5

1. Alkai metals (blows up in water)
2. Alkaline earth metals
   
   17. Halogens (makes mustard gas)
   18. Noble gases / inert gases (don’t do anything)
       3 - 12. Transition metals (bridge gap between main group elements
       bar under table. inner transition metals

Question 6

Composition of Atoms

Answer 6

• atomic number (z) = number of protrons (p+)
• p+ = if positively charged in the nucleus, if nuetreal, number of protrons = number of nuetrons, not charged and outside of nuecleus
• atomic symbol
• atomic mass (a) find using protrons and nuetrons

Question 7

Ion

Answer 7

charged particle based on lost / gain;
+) Cation = lost e-
-) Anion = gain e+

Question 8

Democritos (2500 BCE)

Answer 8

Believed when something gets to it’s smallest level it is uncutable “atomos”

Circle Model, tiny needles

Question 9

Dalton (1808)

Answer 9

Dalton developed “Modern Atomic Theory” that says
- All matter is made of tiny indivisiable particles
- Atoms of same element are same element
- Two or more atoms in a fixed ratio (whole number) is a compound
- Atoms can combine, compounds can be broken, this is a chemical reaction, but atoms don’t change

Circle Model

Problems:
- atoms can be broken
- not all same element is the same
- nuclear reaction does change element

Question 10

Thomas (1897)

Answer 10

Catho Ray tube expierement (beam has negative charge)

• found positive magnet makes electricity moves toward it
• found negative magnet makes electricity move away from it
• beams mass is 1/1890 hydrogen mass

Thomas discovered first subatomic particle = electron

Developed plum pudding model = Electrons swim in a positive pool inside atom

Question 11

Rutherford - Thomson’s student (1911)

Answer 11

believed things should pass through atom because everything has a heavier mass than the atom

Gold Foil Expieriment
- shoot radioactive stuff as foil and see where it goes

found that 99.9999% went straight through the foil, but 0.0001% randomly flew off in different directions

Conclution:
atom is mostly empty space, with one small dense center of mass (nucleus)

Developed Nuclear model;
Ring of electrons circling one proton

Question 12

Bohr (lowkey not important)

Answer 12

Planetary model:
like the solar system, the electrons orbit the nucleus

Question 13

Isotopes

Answer 13

Atoms that have the same number of protons but a different number of neutrons (mass.)

Question 14

Isotopic Notation

Answer 14

Shorthand way of representing an isotope of an element.

top number is the mass number (#p + #n)
bottom number is the atomic number (#p)

May also be written: chlorine-37 or Cl-37

The actual average atomic mass for all chlorine isotopes is 35.45 amu

Question 15

Atomic mass

Answer 15

The mass of an atom expressed in amu (atomic mass units.)

One amu is equal to 1/12 the mass of a carbon-12 atom.

Question 16

Average Atomic mass

Answer 16

The weighted average of all an element’s isotopes.

This is the number shown in the box on the Periodic Table.

It is calculated by: (mass1 x %1) + (mass2 x %2) + …