Atomic Structure

Question 1

What is an atom?

Answer 1

Atom is the smallest unit of matter.
(the smallest component of all living and non-living materials)

Atoms consist of electrons circling nucleus of the atom (nucleus consists protons and neutrons)

Atoms are electrically neutral. This is because the number of protons and electrons are equal.

Question 2

What is shell/orbit?

Answer 2

The circular paths of the electrons, which are negatively charged.
The nucleus is orbited by electrons.
(energy level)

Question 3

A-E-M-C

Answer 3

Atoms - Element - Molecule (two or more atoms join together, can be the same or different atoms) - Compound (two different elements join together)

Question 4

What is valence electrons?

Answer 4

in the outermost shell

Question 5

Cations? Anions?

Answer 5

Ions are atoms or molecules which have gained or lost one or more valence electrons, giving the ion a net positive or negative charge. There are cations and anions.

Cation is formed when an atom loses electrons. Since now there is more protons than electrons, cation carries a net positive charge.

Question 6

What is atomic number?

Answer 6

The number of protons in an atom

Question 7

Mass Number

Answer 7

most of the mass of an atom lies in its nucleus because protons and neutrons are much heavier than electrons

mass number is the number of protons added to the number of neutrons

Question 8

Isotopes

Answer 8

Atoms with the same number of protons but with different numbers of neutrons (= Isotopes of an element posses the same atomic number, but different mass numbers)

Question 9

Relative Atomic Mass

Answer 9

The relative atomic mass of an element is the average value for the isotopes of the element. It takes into account the percentage abundance of the isotopes

Question 10

Mass spectrometer

Answer 10

mass spectrometer is used to find the isotopic masses and abundance of isotopes in a sample of an element

Question 11

Mass spectrometer - 1

Answer 11

“vaporisation chamber”

turns sample into a gas

Question 12

Mass spectrometer - 2

Answer 12

“ionisation”
Electron gun ionises the sample.
electrons are fired at the gaseous sample. If one of these electrons collides with an atom, it may push out an electron from the atom, making a positive ion

Question 13

Mass spectrometer - 3

Answer 13

“Acceleration”

charged plates: accelerates the sample

Question 14

Mass spectrometer - 4

Answer 14

vacuum pump

removes air particles, unionised sample; solvent

Question 15

Mass spectrometer - 5

Answer 15

magnet (deflection)
deflects the ions according to mass-to-charge ratio
because a strong electromagnet surrounds the chamber, the ions are bent downwards. The degree of bend experienced by an ion depends upon its m/z value and upon the strength of the magnetic field. For ions of a particular m/z ration, there will be only one value of magnetic field strength which will bend those ions so that they strike the detector.

Question 16

Mass spectrometer - 6

Answer 16

detector (detection)
ions of particular m/z ratio are brought down to the ion detector one by one. A plot of signal intensity against m/z shows the relative abundance of isotopes for that element.

Question 17

mass-to-charge ration foluma?

Answer 17

mass of cation/charge of cation