The Atom

Question 0

compound

Answer 0

is a combination of atoms together to form a new substance

Question 1

element

Answer 1

is a substance made from only one type of atom. An element cannot be broken down into smaller substances

Question 2

Democritus

Answer 2

proposed that all matter is made up of smaller, indivisible particles, which they named atomos

Question 3

atomos

Answer 3

indestructable

Question 4

john dalton

Answer 4

1700’s/early 1800’s
matter is composed of tiny indivisible particles called atoms
all atoms of the one element are identical but are different from the atoms of other elements
Chemical reactions consist of rearranging atoms in simple whole number ratios

Question 5

Sir JJ Thompson

Answer 5

1897
discovered the electron using a Crooks Tube
Plum Pudding model

Question 6

Sir Ernest Rutherford

Answer 6

1911
Gold foil experiment
orbital model
discovered the nucleus
electrons orbit the nucleus
most of the mass of the atom is in the nucleus
nucleus contained positively charged particles (protons)
number of protons are equal to the number of electrons

Question 7

Sir James Chadwik

Answer 7

1932
discovered the existence of the neutron in the nucleus (electrically neutral particles with a mass similar to that of a proton.
bombarded beryllium with alpha particles and discovered Rutherford’s missing neutral particles
explained the existence of isotopes

Question 8

atomic mass unit

Answer 8

a.m.u.
mass of a proton
neutrons and protons have the same amu

Question 9

electron amu

Answer 9

1/1840amu

Question 10

collective name of the particles in the nucleus

Answer 10

nucleons

n˚ + p+

Question 11

nucleons are held together by

Answer 11

nuclear glue

Question 12

Atomic number

Answer 12

the total number of protons that are found in the nucleus of an atom
also represents the total number of electrons orbiting the nucleus in the neutral atom.
represented by Z

Question 13

Mass number

Answer 13

(A)
the collective sum of the number of protons and neutrons (number of nucleons) that are present in the nucleus of an atom
A = n˚ + p+

Question 14

nuclear formula

Answer 14

n˚ = A - Z

Question 15

Isotope

Answer 15

are atoms of an element that have the same number of protons, but differing numbers of neutrons in their nuclei - that is, they have differing numbers of neucleons

Question 16

Relative atomic mass

Answer 16

(Ar)
Average relative mass amu.
Ar = (A1 x %) + (A2 x %) + (A3 x %)
100 100 100

Question 17

Niels Bohr

Answer 17

Explained the orbiting of electrons
Planetary model
electrons move around the nucleus in fixed orbits. An electron in a particular orbit has constant energy
an electro can absorb energy and move to a higher energy orbit of larger radius when excited
an excited electron can fall back to its original orbit by emitting energy as radiation
electrons can only exist in certain discrete orbitals

Question 18

Planetary model energy levels

Answer 18

K orbit = max 2 electrons
L orbit = max 8 electrons
M orbit = max 18 electrons
N orbit = max 32 electrons

Question 19

energy level

Answer 19

area of probability in which an electron would be found orbiting the nucleus of an atom and that these electrons would have energy typical of that region of probability.

Question 20

Region of probability orbital classification

Answer 20

s orbital
p orbital
d orbital
f orbital

Question 21

orbitals

Answer 21

these are areas within an energy level in which electrons are allowcated. The orbitals do vary slightly in energy where the s orbital will have the lowest energy within the level, then the p orbital, then the d orbital followed by the f orbital.

Question 22

Aufbau principle

Answer 22

the energy structure of a multi electron atom is obtained by filling the orbitals one electron at a time, in order of increasing energy starting with the lowest energy.

Question 23

4s orbital

Answer 23

has less energy than the 3d orbital and thus it will follow the 3p orbital.

Question 24

Pauli’s exclusion principle

Answer 24

if electrons are placed close to each other, electrostatic forces of repulsion will be present between them.
determined that electrons have opposite spins, which reduced the force of repulsion

Question 25

Hunds rule of maximum multiplicity

Answer 25

electrons tend to occupy the orbitals one by one and not pair up.

Question 26

electron confuguration

Answer 26

1s ^2

orbital amount of electrons in the orbital

Question 27

GroupI
GroupII
GroupVI
GroupVII
GroupVIII

Answer 27

Alkali metals
Alkaline metals
Chalogens
Halogens
Noble Gases

Question 28

Valence electrons

Answer 28

the number of electrons that are found in the highest energy level of an atom

Question 29

Core Electrons

Answer 29

the electrons found in the lower energy levels beneath the highest (valence) energy level. These electrons will ensure that the lower energy levels are full.