SACness. – Chemistry Flashcard

What did Robert Boyle propose?
That a substance is an element unless it can be broken down into simpler substances.
Which element did Antoine Lavoisier discover?
Oxygen.
Which two laws did Lavoisier formulate?
Law of Conservation of Mass and Law of Constant Proportion.
Explain the Law of Conservation of Mass.
Basically, mass can not be created nor destroyed.
Explain the Law of Constant Proportions.
“The same compound, however formed, contains the same elements chemically combined in constant proportions by weight.”
What were John Dalton’s correct statements?
All matter is comprised of atoms, atoms are held together by forces of attraction, atoms off different elements have different masses, atoms form the smallest part of an element, chemical reactions occur when atoms are joined, separated or re=arranged, compounds are substances that are formed from the combination of two or more atoms and the proportion and nature of atoms is fixed within a given compound.
What were John Dalton’s incorrect statements?
Mainly :The atom is a solid sphere and compounds are most stable when they combine on a one to one ratio
But also: Atoms are not divisible and connot be created or destroyed and atoms of the same element are identical and have the same mass.
Is Michael Faraday really that important?
No, not really.
What did Michael Faraday do?
Passed a large current through a glass tube that had most of its air pumped out and observed a glow that was later shown to be caused by rays that travelled from the cathose (negatively charged electrode) towards the anode (positively charged electrode). These rays were subsequently called “cathode rays”.
What did Joseph John Thompson do?
Proposed the plum pudding model and discovered negatively charged particles (electrons) that were present in the atoms of all elements.
What did Frederich Soddy do?
Not a sodding lot BAHAHA! But really, he showed that isotopes exist.
Which experiment did Ernest Rutherford carry out, and what did he conclude from its results?
The gold foil experiment (alpha rays (helium nuclei) at gold sheet, blah blah_ He concluded that an atom was comprised mainly of empty space containing electrons and that most of the mass and all of the positive charge was concentrated in one small central mass (the nucleus).
What did Rutherford propose?
That the diameter od the atoms is ten to the power of four times the diameter of the nucleus (don’t need to know that really) and that the nucleus contains neutrally charged particles called neutrons.
Niels Bohr. What did this guy do?
Used the emission spectra to devise a new model for the atomic structure. He said that an atom’s electrons could only exist in definite orbits called shells and that these shells, also called energy levels, are located at different distances from the nucleus. He said that the orbit in which an electron moves depends on the energy of the electron, that electrons in shells closest to the nucleus have the lowest energies and experience the strongest attraction to the nucleus, that electrons with a low energy level occupies orbits closer to the nucleus, electrons circle the nucleus without loss of energy and that atoms release particular amounts or quanta of energy when electrons in the excited state move back to a lower energy state and these are observed as varying wavelengths of light (ring a bell? emission spectrum!).
Someone explain ground and excited state to me.
Ground state: all the electrons are chilling in their own energy levels, without being given any energy to move.
Excited: more like pissed off. When electrons are given a certain amount of energy, they move further out from the nucleus AND THEY DON’T LIKE IT. Because they hate it soooo much, they give the energy back and go back to where they were before, thanky very much.
NB: Electrons can’t accept energy that will send them halfway to the next shell. They will only take the exact amount that will take them to another shell. Fussy, fussy,
So what do the lines on an emission spectrum represent?
The different energy levels present in a particular atom.
So what do the lines on an emission spectrum represent?
The different energy levels present in a particular atom.
So what do the lines on an emission spectrum represent?
The different energy levels present in a particular atom.
So what do the lines on an emission spectrum represent?
The different energy levels present in a particular atom.
So what do the lines on an emission spectrum represent?
The different energy levels present in a particular atom.
Why do no two elements produce the same emission spectrum?
Each element has a different number of protons in the nucleus and this the attraction between the nucleus and the electrons will vary between elements. NO TWO ELEMENTS will have shells of the same energy so their spectra are different.
Easy one for you – what’s ionisation energy?
The amount of energy required to remove the outermost electron from an atom (in the gaseous state).
What does an atom’s ionisation energy value depend on?
the forces of attraction that exist between the nucleus and electron(s) being removed.
Why does the ionisation energy of an atom increase with the successive removal of electrons?
Because each time an electron is removed, the remaining electrons have a greater share of the nuclear charge, making them harder to get out and because the remaining electrons are closer to nucleus and thus are more strongly attracted.
What did Schrodinger say?
That electrons behave in a wave like manner around the nucleus. Through the observation of the clusters of lines on the emission spectra, he concluded that shells contained further energy levels referred to as subshells and orbitals.
James Chadwick did one thing. What was that one thing?
Discovered the neutron.
How do we now know the electron behaves? (badly worded, soz)
It behaves like a cloud of negative charge.
What are the names of the four subshells?
s, p, d and f.
Which of the following subshells does not exist?
4d.
3p.
2d.
2p.
2d.
How many orbitals are located in:
the s subshell
the p subshell
the d subshell
the f subshell
1, 3, 5 and 7 respectively.
What is the mass number of an atom?
The total number of protons and neutrons in the atom’s nucleus.
What is an atom’s atomic number?
The number of protons in an atom’s nucleus.
What are isotopes?
Atoms of the same element that have different numbers of protons (and masses).
What did Mendeleev base the periodic table’s arrangement on?
Relative atomic mass (periods) and chemical properties (groups).
What happens to the ionic charge and atomic radius of atoms as you go down a group?
Stays the same and gets bigger, respectively.
Explain the relationship between electronegativity and atomic radius.
When an atom has a higher electronegativity, it pulls its electrons in closer, making its atomic radius smaller.
What happens to the electronegativity and atomic radius of atoms ad you go across a period?
Increases and decreases, respectively.
What is an atom’s core charge?
The amount of charge acting on the outer shell electrons (not applicable to ions). As the electrons in the completely filled inner shells act as a shielding, the core charge is less than the nuclear charge.
What happens to core charge and number of valence electrons as you go across a period?
They both increase.
What happens to first ionisation energies as you move across a periods? Why is this?
They increase. The atoms’ electronegativities increase, making it harder to remove electrons.
What happens to first ionisation energies as you go down a group? Why is this?
They decrease. Because the atoms’ electronegativities decrease, making it easier to remove electrons.

Get instant access to
all materials

Become a Member