C1 Flashcards
Atom Definition
Smallest Part Of An Element That Can Exist
Molecule
Cluster Of Non-Metal Atoms Chemically Bonded Together
Element
Substance That Contains One Type Of Atom
Compound
Two Or More Elements Chemically Combined In Fixed Proportions.
Who first proposed the idea that the atom wa sthe smallest thing?
Democritus
What did Dalton’s evidence support?
The idea that atoms existed.
They were tiny spheres that couldn’t be divided.
What did JJ Thompson discover and when?
In 1897, he discovered that atoms are made up of smaller particles.
He then made his plum pudding model.
What was the Geiger-Marsden-Rutherford experiment?
Fired alpha particles (large positively charged particles) at very thin gold foil.
What were the results of the Geiger-Marsden-Rutherford experiment and what did they inidcate?
Most of the alpha particles went straight through the gold particles - Atoms are mainly empty space.
Some of the alpha particles were deflected - Center of an atom must have a positive charge.
Some of the alpha particles bounced straight back - Center of an atom must contain a great deal of mass.
What did Bohr propose and when?
In 1913, Electrons orbit the nucleus in fixed shells or orbitals located at set distances from the nucleus.
What did Chadwick prove and when?
Proved the existence of neutral particles called neutrons. 1932.
What are the relative masses of the subatomic particles?
Electrons - Negligible
Protons - 1
Neutrons - 1
What is the Atomic Number?
The number of Protons.
What is the Mass Number?
Number of Protons + Number of Neutrons
What determines what type of atom one is?
The number of protons.
What is the name of the outermost shell?
Valence Shell
What does the cell become if the outer shell is full?
Much more stable
What is the rough radius of an atom?
1 x 10^-10 meters
What are Ions?
Particles with a different number of protons and electrons so are electrically charged.
Rough size of an atom’s nucleus in relation to the atom?
Less than 1/10,000 of the atom
What are Isotopes?
Atoms of the same element with different numbers of neutrons and the same number of protons.
Why do isotopes of the same element have the same characteristics and chemical properties?
Because they have the same number of electrons in their outer shell.
Calculating the relative mass of an atom.
(% of Isotope a x Mass of Isotope a) +
(% of Isotope a x Mass of Isotope a)
/
100
What is relative atomic mass equal to?
1/12 of the mass of a Carbon-12 atom.
What do Ions have the same stable electron structure as?
Noble Gases
Which elements react to form posistive ions?
Metals
What did the Plum Pudding Model suggest?
The atom is a ball of positive charge with negative electrons embedded in it.
Where is the majority of an atom’s mass found?
Its nucleus
How can compounds be separated?
Chemical Reactions
Group 1
Alkaline Metals
Group 7
Halogens
Group 0
Noble Gases
Examples of Physical Change:
No new substance produced.
Inolves the forces of attraction between particles.
Examples include: melting point, boiling point, density, conductivity.
Examples of Chemical Change:
New substance produced.
Involves the transfer/sharing of electrons.
Examples include: reactions with oxygen and water.
How many electrons are in the valence shells of an Alkali Metal?
1
Before the discovery of subatomic oarticles, how did scientists classify elements?
In order of their atomic weights
Who changed the classification of elements?
Mendeleev
Elements that do not form positive ions
Non-Metals
What happens to the boiling point of the Noble Gases as their relative mass increases?
Increases
What happens to the reactivity of the Alkali Metals as you go down the group?
Increases
Number of electrons in the valence shell of the Halogens?
7
What do the Halogens consist of?
Molecules made of pairs of atoms.
What happens when you go down the the Halogens group?
The relative molecular mass, boiling point and melting point increase.
The reactivity decreases.
What does a more reactive halogen do to a less reactive halogen in an aqueuous solution of its salt?
It displaces it
Who began developing the idea of a periodic table 140 years ago?
John Newlands
What to do for a Six Marker?
Do a labelled diagram of the atom, draw the electrons and add the neutrons and protons.
Say the number of protons, neutrons and electrons.
Say the group and period and the feasons why.
Say the electron configuration.
