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15 Cards in this Set
- Front
- Back
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Atom |
Smallest part of an element which can ever exist on its own |
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Molecule |
The smallest part of a substance which can exist under normal conditions |
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Isotopes |
-Atoms of the same element having same proton number but different nucleon number(proton number + number of neutrons) -They have same chemical properties but different physical properties -The % by mass of each isotope in a given sample of the element is the relative abundance of the isotope -monoisotopic elements are elements existing in only one isotopic form |
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The relative isotopic mass (r.i.m) |
It is the mass of an isotope of an element compared to 1/12 the mass of the predominant isotope of carbon, C-12, which is assigned a mass of 12 |
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Relative atomic mass (Ar) |
The weighted average mass of an atome compared to 1/12 the mass of the predominant isotope of carbon, C-12 which is assigned a mass of 12 |
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Relative molecular mass (Mr) |
The average mass of molecule compared to 1/12 the mass of the predominant isotope of carbon, C-12 which is assigned a mass of 12 |
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Relative formula mass |
-The average mass of a formula unit compared to 1/12 the mass of the predominant isotope of carbon, C-12 which is assigned a mass of 12 -Symbol: Mr |
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Mass spectrometer |
It is used to: (1)measure the r.i.m of different isotopes of an element (2)measure the relative abundances of each isotope of the element (3)measure the Mr of different substances (4)suggest the possible group of atoms which are present in a molecule (5)calculate the num of carbon atoms that are present in the molecule of a compound (6)verify whether an organic molecule contains an atom of chlorine or an atom of bromine |
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The mass spectrograph |
The mass spectrograph of an element shows: (1)the num of isotopes of the element present in the sample (2)the r.i.m of each isotope The mass spectrograph of monoisotopic molecular elements consists of a set of equidistant peaks =the number of peaks shows the number of atoms present in a molecule of the element =the 1st peak indicates the r.i.m of the element =the last peak indicates the molecular mass of the element |
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Mass spectrograph of organic compounds |
=The last peak shows the relative molecular mass of the compound. It is usually the shortest peak since most of the molecules undergo fragmentation when they pass through the ionisation chamber =The remaining ingredients peaks are fragmented peaks |
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Mole |
The amount of substance that contains 6.02×10*23 particles n=mass(g)/Mr |
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Avogadro's law |
It states that equal volume of gases measured under same conditions of temperature and pressure ontain the same number of moles, I.e, same number of molecules =at rtp, 1 mol of any gas has a volume of 24 dm^3 =at stp, 1 mol of any gas has 22.4 dm^3 Note:these volumes are referred to as molar volume =at rtp, n=V dm^3/24 dm^3 =at stp, n=V dm^3/22.4 dm^3 |
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Empirical formula |
Simplest whole number ratio of different elements present in a compound |
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Molecular formula |
Gives actual number of atoms of different elements present in a compound |
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Combustion of hydrocarbons |
CxHy +(x+y/4)O2 ====>xCO2+(y/2)H2O |
