atomic structure & periodic table

Question 1

what was john dalton’s theory on atoms

Answer 1

all matter is made from atoms
they cannot be created or destroyed
they are tiny, hard spheres
the atoms of an element are identical

Question 2

what did cathode rays show

Answer 2

that when a high voltage is applied to a glass tube has most of the air removed, glowing rays are seen
JJ Thomson weighed the particles in the cathode rays and they were much lighter than the lightest atom, meaning that they were subatomic particles called electrons

Question 3

what is the relative mass of a
proton
electron
neutron

Answer 3

p = 1
e = negligible (almost zero)
n = 1

Question 4

what is the relative charge of a
proton
electron
neutron

Answer 4

p = +1 (positive)
e = -1 (negative)
n = 0 (no charge)

Question 5

what is in the nucleus of an atom

Answer 5

protons and neutrons

Question 6

why do atoms have no overall charge

Answer 6

because they always have equal numbers of protons and electrons, so their positive and negative charges cancel each other out

Question 7

why is most of the mass of the atom in nucleus

Answer 7

because the rest of the atom is empty space and electrons which weigh a negligible weight

Question 8

how does the modern periodic table order the elements

Answer 8

by atomic number (number of protons)

Question 9

what does the number in the top corner of the element represent

Answer 9

mass number (protons + neutrons)

Question 10

what does the number in the bottom corner of the element represent

Answer 10

atomic number (protons only)

Question 11

who discovered the neutron

Answer 11

james chadwick

Question 12

why do isotopes explain how atoms of the same element can have different masses

Answer 12

because they have different amounts of neutrons which affect the weight

Question 13

how did the understanding of neutrons lead to the discovery of nuclear energy

Answer 13

by firing neutrons at a uranium isotope, the nucleus could be split (nuclear fission) creating new elements and nuclear energy

Question 14

what is the RAM of an element

Answer 14

the relative atomic mass is the mean mass of an atom compared with carbon-12, it takes into account isotopes and the amounts of each isotope. this means that RAMs are usually not whole numbers

Question 15

how did mendeleev organise his periodic table

Answer 15

in order of increasing relative atomic masses but leaving some gaps for undiscovered elements and sometimes swapped some elements if it better suited their chemical properties

Question 16

how are columns (groups) on the periodic table organised

Answer 16

similar chemical properties

Question 17

how are rows (periods) on the periodic table organised

Answer 17

order of increasing atomic number

Question 18

What did Henry Moseley discover

Answer 18

that the atomic number was equal to the number of protons in the atom’s nucleus, this was discovered by firing high energy electrons at different elements making them give off X-rays

Question 19

where are the non-metals on the periodic table

Answer 19

on the right of the table

Question 20

what is electronic configuration

Answer 20

the way in which an atom’s electrons are arranged

Question 21

in the first 20 elements, what is the maximum amount of electrons the first three electron shells

Answer 21

2.8.8

Question 22

how do you figure out electronic configuration

Answer 22

from the atomic number (number of protons = number of electrons)

Question 23

how is electronic configuration related to the periodic table

Answer 23

• the number of occupied shells is equal to the period number
• the number of electrons in the outermost shell is the group number (group 0 elements have a full outermost shell)

Question 24

what is a common chemical property for group 0 elements

Answer 24

being unreactive

Question 25

how many elements were there in Mendeleev’s periodic table compared to the modern periodic table

Answer 25

mendeleev = 63
modern = 118

Question 26

what is a compound

Answer 26

and atom chemically combined with other atom(s)

Question 27

what is group 1 of the periodic table called

Answer 27

alkali metals (extremely reactive)

Question 28

what happens when an alkali metal reacts with water

Answer 28

enough energy is released to melt the metal

the metal floats on the surface

Question 29

key features of a chemical reaciton:

Answer 29

at least one new substance is created, no atoms are created or destroyed, compounds are broken up or formed, often a detectable energy change

Question 30

what did ernest rutherford discover

Answer 30

that alpha particles can bounce back off atoms

Question 31

who discovered that electrons orbit the nucleus at fixed distances

Answer 31

Niels Bohr

Question 32

what is the average radius of an atom

Answer 32

0.1 nanometres

Question 33

what are the three isotopes of hydrogen

Answer 33

protium, deuterium, tritium

Question 34

what are nuclides

Answer 34

have the same proton number, different nucleon number

Question 35

how do you calculate relative atomic mass

Answer 35

(isotope abundance x isotope mass number) / isotope abundance

Question 36

who was the first person to devise a periodic table

Answer 36

John Newlands

Question 37

what are some properties of metals

Answer 37

high melting and boiling points, good conductors of heat and electricity, solids at room temp (except mercury), lose electrons when they react