Ch 3

Question 1

Dalton’s atomic theory (what’s still true vs what’s false)

Answer 1

True
- all matter is composed of extremely small particles called atoms
- atoms cannot be created or destroyed
- Atoms of different elements can combine in simple whole number ratios to form chemical compounds
- in chemical reactions, atoms are combined, separated, or rearranged

False
- atoms cannot be subdivided
- Atoms of a given element are identical in size, mass, and other properties. Atoms of different elements differ in size, mass, and other properties

Question 2

Updated atomic theory

Answer 2

1. An atom is composed of smaller particles (electrons, protons, and neutrons).
2. All atoms of an element are not identical. The existence of isotopes illustrates this phenomena.
3. Through the use of nuclear reactions, atoms of one element can be changed into atoms of another element.

Question 3

Dimitri Mendeleev

Answer 3

Organized all the known elements according to similar properties
He left gaps for what he thought were undiscovered elements & made bold assumptions about their properties
Based on empirical observation, ordered by atomic mass

Question 4

Moseley

Answer 4

credited with the origin of the modern periodic table

discovered that the underlying foundation of the order of the elements was by the atomic number

Question 5

Period

Answer 5

Each row of elements on the periodic table

Question 6

Group/family

Answer 6

Each column on the periodic table

Question 7

Metal

Answer 7

Shiny
Typically silvery in color
Excellent conductor of heat & electricity
Malleable & ductile

Question 8

Nonmetal

Answer 8

Dull
Poor conductor
Brittle when solid

Question 9

Metalloids

Answer 9

Properties intermediate between metals & nonmetals

Question 10

Alkali metals

Answer 10

Common in nature & daily life

Question 11

Alkaline earth metals

Answer 11

Some rare, some abundant
Radium = unstable & radioactive

Question 12

Halogens

Answer 12

“Salt-forming”
React readily with metals to form compounds

Question 13

Noble gases

Answer 13

Composed of only single atoms (monatomic)
Lack of reactivity

Question 14

Discovery of the proton

Answer 14

cathode ray tube produced invisible rays that come from a negative electrode to a positive electrode; these rays could be bent by magnetic/electric fields proving charged particles

Question 15

Discovery of the electron

Answer 15

by measuring the extent of the deflection of the cathode rays in magnetic fields of diff strengths, could then calculate the mass-to-charge ratio of the particles; b/c like charges repel & opposite charges attract, conclusion that particles had a net negative charge

Question 16

Discovery of the neutron

Answer 16

Upon hitting a beryllium nucleus with alpha particles, a neutron particle was emitted

Question 17

amu of the subatomics

Answer 17

Proton = 1 amu
Neutron = 1 amu
Electron = 0 amu

Question 18

Atomic #

Answer 18

Z
# of protons