atomic structure

Question 1

Who were the first people to proprose that matter was made up of particles of elemental substances?

Answer 1

The greeks

Question 2

What became of the Greek views of matter?

Answer 2

it faded

Question 3

What were Democritus (460-370) ideas about matter?

Answer 3

1. smallest paticles of matter are called atoms
2. different type of atoms for every type of matter

Question 4

Democritus ideas about matter were not useful in a scientific sense. why?

Answer 4

1. no experimental evidence to support it
2. did not explain the chemical behavior of atom

Question 5

What did Robert Boyle do in the 1600s?

Answer 5

showed that gold and silver were elements and are not made up of fire, water, wind and earth

Question 6

What was Dalton’s model of atom? What was it’s purpose?

Answer 6

1. cannon ball
2. proposed that atoms were tiny hard sphere

Question 7

Which sub-atomic particle is the first to be discovered in the atom?

Answer 7

The electron in 1871

Question 8

Who discovered the electrons?

Answer 8

J.J Thompson

Question 9

Who made the plum pudding?

Answer 9

J.J Thompson

Question 10

Which scientist 1st discovered the nucleus?

Answer 10

Ernest Rutherford in 1911

Question 11

HOw did he discover the nucleus?

Answer 11

By finding alpha particles at gold foil

Question 12

What did Rutherford observed?

Answer 12

1. most alpha particles went straight through the gold foil
2. only a few alpha particles wee deflected when they came close center of the atom

Question 13

Why most alpha paticles passed straight through the gold foil?

Answer 13

b/c atoms is mainly made up of empty spaces

Question 14

Why were a few alpha particles deflected?

Answer 14

b/c of repulsion between the alpha particles and the central core of atom

pos + pos = repulsion

Question 15

What is the atom mostly made up of?

Answer 15

empty spaces

Question 16

What are the characteristics of the nucleus?

size, density, location, charge

Answer 16

1. much smaller than atom
2. very dense, contains most of the atoms mass
3. center of the atom, central core of the atom
4. positive charge

Question 17

What did Bohr proposed about atoms?

Answer 17

The atom has a very small, positively charged nucleus. Surrounded by electons orbiting the nucleus in energy levels

Question 18

What was Bohr’s model of atom called?

Answer 18

The Planetary MOdel

Question 19

WHy was Bohr’s model of the atom not accepted?

Answer 19

b/c experimental evidence did not support it

Question 20

Wave Mechanical Model ( current model)

( 5 bullet points)

Answer 20

1. matter consists of mass of partiles
2. energy consists of waves
3. evidence showed that the electron has both mass and wave like properties( dual nature)
4. this dual nature of the electron has been incorporated in the most of the most curren model of atom called wave mechanical model
5. in the wave mechanical model the electrons are located in orbitals

Question 21

What are oribitals?

Answer 21

Orbitals are regions in which the electrons are most likely or probably to found. In the orbitals the electrons move with distinct energy

Question 22

Describe an atom.

( 2 bullet points)

Answer 22

1. atom is the smallest particle of an element that etains the chemical properties of that element
2. contgains a small dense, positively charged nucleus srrrounded by a large space occupied by electrons

Question 23

What particles are found in the nucleus?

Answer 23

1. protons and nuetrons
2. the particles found in the nucleus are collectively called nucleons
3. # of nucleons = # of protons + # of neutrons

Question 24

What is the overall charge of an atom?

Answer 24

over charge - all atoms is electrically neutral or zero

Question 25

what is the formula to the overall charge of the nucleus?

Answer 25

nucleus charge = # of protons in nucleus

Question 26

WHat is meant by the term "atomic number?"

Answer 26

this is the number or protons in the nucleus of an atom atom # = # of protoms

Question 27

why don't two elements have the same atomic number?

Answer 27

because each element has a unique number of protons in its nucleus, no two elements have the same atomic #

Question 28

What is meant by the term " mass number"

Answer 28

sum of protons and neutons in the nucleus of an atom **_mass number = # of protons + # of neutrons_**

Question 29

how do we find the number of neutrons?

Answer 29

neutrons = mass # - atomic #

Question 30

Where outside the nucleus are the electrons to be found?

Answer 30

1. electrons ae found outside the nucleus in principle energy levels or shells 2. each principal energy level can only hold a certain amount of electrons

Question 31

Principal energy level (n) n = 1 energy level n=2 energy level n=3 energy level n= 4 energy level

Answer 31

1. 2 2. 8 3. 18 4. 32

Question 32

which electron enery level has the lowest energy

Answer 32

1st energy level

Question 33

what is meant by tht eterm electon configuration?

Answer 33

Electon configuration shows the distribution of electons in an atom

Question 34

What are valence electrons?

Answer 34

Valence electrons are electrons in the outermost principal energy or shell **_# of valence electrons = # of electrons in the outemost shell_**

Question 35

What is the Lewis Dot Diagram ?

Answer 35

consists of a chemical symbole surounded by one to eight dots representing valence electrons

Question 36

What are isotopes?

Answer 36

Isotopes are atoms of the same element that have the same number of protons and electrons but different number of neutrons OR Isotops are atoms of the same element of having the same atomic number different mass number

Question 37

What is atomic mass?

Answer 37

1. the atomic mass of an element is the average mass of all naturally occuring isotops of that element 2. the atomic mass of an element is usually closest to the isotope with the highest natural abundance

Question 38

What are electrons said to be in ground state?

Answer 38

when they occupy the lowest available energy levels

Question 39

What happens when energy ( heat, light or electic) is applied to electons in the gound state?

Answer 39

The electrons in the ground state absorbs the energy and move up to higher energy level

Question 40

What are these higher energy level called?

Answer 40

Excited states

Question 41

Describe the electrons in excited states

Answer 41

electrons in the excited states have high energy and are very unstable

Question 42

What will eventually happen to the electrons in the excited state?

Answer 42

They quickly return to the ground state by releasing energy to the form of **_light_**

Question 43

WHat are the lines called shown through a spectroscope?

Answer 43

bright line spectrom or emission lines

Question 44

Why are spectral lines known as fingerprints of elements?

Answer 44

Each element has its own unique bright line spectrum

Question 45

What is an ion?

Answer 45

an ion is an electrically charged particle

Question 46

What charge can an ion have?

Answer 46

positive and negative

Question 47

Describe a positive ion | (3 bulletpoints)

Answer 47

1. A positive ion will have more psitively charged protons than negatively charge electrons 2. positive ions called cations 3. positive ions are formed when an atom loses lectrons there ions how formed will have more portons than electrons

Question 48

Describe negative ions | (3 bulletpoints)

Answer 48

1. a negative ion will have more negatively charge electrons than positively charge protons 2. negative ions called **_anions_** 3. negative ions are formed when an atom gains electrons therefore the ion now formed will have more electrons than protons