Yr9 recap test Flashcards
What did the discovery of the electron lead to?
The plum pudding model
What did the plum pudding model suggest about atoms?
That the atom was a ball of positive charge with negative electrons embedded in it
What did the results from the Rutherford and Marsden’s alpha scattering experiments lead to?
The plum-pudding model being replaced by the nuclear model.
In the nuclear atom model, what is the centre of the atom called?
The nucleus
What did the ‘alpha scattering’ experiment show?
. That all the mass of the atom was in the nucleus
. That all the positive charge of the atom was in the nucleus
How are electrons placed in the nuclear model?
The electrons were thought to orbit the nucleus, like planets around the sun.
What happened to most of the alpha particles in the ‘alpha scattering’ experiment? What did it prove?
Most of the alpha particles directed at thin gold foil passed through showing that
that all the mass of the atom was in the nucleus.
What happened to a few of the alpha particles in the ‘alpha scattering experiment’? What did it prove?
A few alpha particles were deflected or bounced back, suggesting the positive charge was concentrated at the
centre of each gold atom.
How did Neils Bohr adapted the nuclear model?
By suggesting that electrons orbit the
nucleus at specific distances
Where are electrons on the Bohr model?
The electrons are on energy levels or shells
What did later experiments (after Bohr) lead to?
The idea that the positive charge of any nucleus could be subdivided into a whole
number of smaller particles, each particle having the same amount of positive charge. The name proton was
given to these particles.
What did the experimental work of James Chadwick provide the evidence to show?
The existence of neutrons within the
nucleus.
How long after the nucleus was discovered was neutrons discovered?
About 20 years after the nucleus became an accepted scientific idea.
What did the discovery of neutrons help explain?
The existence of isotopes
What is the nucleus of the atom made up of?
Protons and neutrons
What orbits around the nucleus of an atom?
Electrons
In an atom what is the number of electrons equal to?
The number of protons in the
nucleus.
Do atoms have an overall electric charge?
NO
What do all atoms of a particular element have?
The same number of protons
Where is most of the mass of an atom
The nucleus
What is an atom’s mass number?
The total number of protons and neutrons in an atom
What is the radius of an atom?
0.1 nm (1x 10-10 m)
What is the radius of the nucleus of an atom?
1/10 000 of that of the atom (about 1 x 10-14 m)
What is the atomic number of an element?
The number of protons in an atom
How are elements arranged in the modern periodic table.
In order of their atomic number (proton number)
How do you work out the number of neutrons in an atom?
Subtract the atomic number from the mass number
What are isotopes?
Atoms of the same element can have different numbers of neutrons
Do isotopes of an element have the same chemical properties
YES because they have the same electronic structure.
What is the relative atomic mass?
An average value that takes account of
the abundance of the isotopes of the element.
What is the relative atomic mass calculation
What do elements in the same group in the periodic table have?
The same number of electrons in the highest energy levels (outer electrons) and this gives them similar properties.
What are the elements in Group 0 of the periodic table called?
The noble gasses
Why are group 0 elements inert?
Their atoms have a stable arrangement of electrons.
How are elements in the periodic table arranged?
In order of atomic number
What are columns in the periodic table known as?
Groups
How did the periodic table get it’s name?
Because similar properties occur at regular intervals.
Elements in the same group in the periodic table have…
…the same number of electrons in their outer shell (outer electrons) and this gives them similar chemical properties.
What does the atomic number of an element give?
The number of protons or
electrons
Elements in the same period…
… have the same
number of shells
As you go down a group…
…the number of shells
increases
How did scientists attempted to classify the elements before the discovery of protons, neutrons and electrons?
By arranging them
in order of their atomic weights.
What was wrong with early periodic tables?
The tables were incomplete and some elements were placed in inappropriate groups if the strict order of atomic weights was followed.
What made it possible to explain why the
order based on atomic weights was not always correct?
Knowledge of isotopes
How did Mendeleev overcome some of the problems of early periodic tables?
By leaving gaps for elements that he thought had not been discovered.
What did Mendeleev predict about the undiscovered elements?
Their properties
What do metals react to form?
Positive ions
What do non-metals react to form?
Not positive ions (hydrogen is exeption)
Where are metals found on the periodic table?
To the left and towards the bottom of the
periodic table.
Where are non-metals found on the periodic table?
Towards the right and top of the periodic table.
What happens to the boiling point of group 0 elements as you go down the group?
The boiling points of the noble gases increase with increasing relative atomic mass (going down the group).
Do group 1 elements have high or low density?
They are metals with low density (the first
three elements in the Group are less
dense than water)
How are group 1 metals safely stored?
They are stored under oil to prevent them
from reacting with oxygen or water.
How do group 1 elements react with non-metals?
They react with non-metals to form ionic
compounds in which the metal ion carries a
charge of + 1.
What does the compound produced when group 1 elements react with non-metals look like?
The compounds are white
solids which dissolve in water to form
colourless solutions.
How do group 1 metals react with water?
Group 1 metals react with water releasing
hydrogen and form hydroxides which
dissolve in water to give alkaline solutions.
(this is why they are known as alkali metals)
Describe how group 1 elements react with water?
They react vigorously with water fizzing and
moving around on the surface of the water.
What happens to the reactivity of group 1 elements as you go down the group?
In group 1, the further down the group an element is the more reactive it becomes
Why does reactivity increase as you go down group 1?
As the atoms get larger the outer electron is
further from the nucleus.
Thus the outer electron is less attracted to the nucleus and so can more easily be lost.
What id the name given to group 7 elements?
Halogens
What do the halogens have?
Coloured toxic vapours
Are group 7 elements diatomic?
YES
What do group 7 elements form when reacted with metals?
Ionic salts with metals in which the chloride, bromide or iodide ion carries a charge of -1
What do group 7 elements form when reacted with non-metals?
Molecular compounds
In group 7, does the relative molecular mass of the elements increase or down the group?
Increase due to increased intermolecular forces
What is a displacement reaction?
When more reactive halogen can displace a less reactive halogen
from an aqueous solution of its salt.
E.g. Cl2 + 2 NaBr Br2 + 2 NaCl
In group 7, does the reactivity of the elements increase or decrease going down the group?
Decrease because…
Going down the group:
* The atoms get bigger
* and so outer shell electrons are
further from nucleus
* Outer electrons less strongly
attracted to nucleus
* can less easily gain electrons.
Where are the transition metals in the periodic table?
between Groups 2 and 3
Compared with the elements in Group 1, do transition metals have higher or lower melting points?
Higher (except mercury)
Compared with the elements in Group 1, do transition metals have higher or lower densities?
Higher
Compared with the elements in Group 1, are transition metals stronger?
YES
Compared with the elements in Group 1, are transition metals harder?
YES
Compared with the elements in Group 1, are transition metals less reactive?
Yes, are much less reactive and so do not react as vigorously with water or oxygen
Many transition elements have ions with…
…different charges
Many transition elements form…
…coloured compounds
Many transition elements are useful as…
…catalysts
