Chapter 4 - Atomic Theory, Atoms, Elements and Ion Notes

Question 1

Dalton’s Atomic Theory

Answer 1

year 1808

1. Elements are made of tiny particles called atoms.
2. All atoms of a given element are identical.
3. The atoms of a given element are different from those of any other element.
4. Atoms of one element can combine with atoms of other elements to form compounds.
5. Atoms are not created or destroyed in chemical reactions. A chemical reaction simply changes the way the atoms are grouped together.

Question 2

JJ Thomsom

Answer 2

1897 discovered electrons in Cathode Ray experiments.

Question 3

E. Goldstein

Answer 3

1900 discovered protons in Anode Ray experiment

Question 4

E. Rutherford

Answer 4

1911 discovered the nucleus and provide the basis for the modern atomic structure through his alpha particle scattering experiment.

Question 5

James Chadwick

Answer 5

1932 discovered neutrons

Question 6

N. Bohr

Answer 6

1940 provided the modern concept of the atomic model.

Question 7

Proton

Answer 7

positively charged particle found inside the nucleus

Question 8

Neutron

Answer 8

uncharged particle found inside the nucleus

Question 9

electron

Answer 9

negatively charged particle found orbiting outside of the nucleus.

Question 10

atomic number

Answer 10

number of protons

Question 11

atomic mass

Answer 11

number of protons plus the number of neutrons

Question 12

number of protons and electrons in a neutral atom are

Answer 12

equal.

Question 13

isotopes

Answer 13

atoms with the same number of protons but with a different number of neutrons. the atomic number stays the same. The atomic mass is different.

Question 14

ions

Answer 14

occur when electrons have been added or removed from a neutral atom.

Question 15

cation

Answer 15

an ion with a positive charge. electrons have been removed

Question 16

anion

Answer 16

an ion with a negative charge. electrons have been added.

Question 17

diatomic elecments

Answer 17

these are molecules made up of 2 atoms of the same element.

Question 18

diatomic elements found on the periodic tables are:

Answer 18

hydrogen (h2), oxygen (O2), nitrogen (n2), fluroine (F2), chlorine (CL2), bromine (Br2) and iodine (I2).

Question 19

Periodic Table

Answer 19

• vertical columns are known as groups
• horizontal rows are known as periods
• elements are organized by increasing atomic number
• elements are categorized as metals, nonmetals or metalloids.
• elements can be solids, liquids or gases at 25 C .

Question 20

Groups

Answer 20

these elements are grouped together based on similar chemical properties

Question 21

group 1

Answer 21

alkali metals

Question 22

group 2

Answer 22

alkaline earth metals

Question 23

group 3

Answer 23

12 transitional metals

Question 24

group 17 or 7

Answer 24

halogens

Question 25

groups 18 or 8

Answer 25

noble gases

Question 26

Element States at room temperature

Answer 26

the majority of elements are solid at room temp (25C)
except:
mercury (Hg) and bromine (br2) are the only two elements that are liquids at 25 C
and
Gases at 25 C are: hydrogen, helium, nitrogen, oxygen, fluorine, neon, chlorine, argon, krypton, xenon and radon.

Question 27

metals

Answer 27

1. conduct heat and electricity
2. malleable - can be hammered into thin sheets
3. ductile - can be pulled into wires.
4. shiny appearance (luster)
5. most are solids at 25 C (room temp)

Question 28

nonmetals

Answer 28

1. brittle
2. usually lack the properties of metals
3. most do not conduct heat or electricity
4. most are no malleable
5. most are no ductile
6. most do not have a shiny appearance (lack luster)

Question 29

mettaloids

Answer 29

1. have a mixture of metallic and nonmetal properties

Si - silicon, As-arsenic, Te-tellurium, Ge- germanium, and Sb- antimony

Question 30

compounds

Answer 30

a compound is composed of 2 or more elements from the periodic table.

Question 31

chemical formulas for compounds

Answer 31

are written with the element symbols and a subscript to indicate the number of each type of atom present.
H2O