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Week 1 Chemie
Basiskennis; atomen, ionen en moleculen
Hoofdstuk 2 Atoms and the Periodic Table
The smallest piece of an element that maintains the identity of that element is called an atom.
The general tenets of Dalton’s atomic theory were as follows:
All matter is composed of extremely small particles called atoms
Atoms of a given element are identical in size, mass, and other properties. Atoms of different
elements differ in size, mass, and other properties.
Atoms cannot be subdivided, created, or destroyed
Atoms of different elements can combine in simple whole number ratios to form chemical
compounds
In chemical reactions, atoms are combined, separated, or rearranged
Atoms are composed of smaller parts called subatomic particles: electron (negative charge, 1 amu),
proton (positive charge) and neutron (neutral, 1 amu).
The relatively massive protons and neutrons are collected in the center of an atom, in a region called
the nucleus of the atom.
A useful unit to measure atomic mass is the atomic mass unit (amu), where 1 amu = 1.660539 x
10^-24 g
Week 1 Chemie 1
, The fundamental characteristic that all atoms of the same element share is the number of protons. This
number of protons is so important to the identity of an atom that it is called the atomic number (Z). The
number of protons in an atom is the atomic number of the element.
Atoms are electrically neutral, meaning that the overall electric charge is zero. This is because the
number of protons equals the number of electrons. Therefore, the atomic number also provides the
number of electrons. Atoms that have a charge are called ions.
Atomic number = Z = p+ = e- (by neutral charge)
The mass number (A) is defined as the total number of protons and neutrons in an atom:
Mass number = A = p+ + n
Atoms of the same element always have the same number of protons, same Z, but often have different
numbers of neutrons, therefore, different mass numbers. These atoms are called isotopes.
Isotopes are atoms of the same element that contain different numbers of neutrons. This difference in
neutron amount affects the mass number (A) but not the atomic number (Z). The figure below shows
an easy way to represent isotopes with a nuclear symbol.
Week 1 Chemie 2
Week 1 Chemie
Basiskennis; atomen, ionen en moleculen
Hoofdstuk 2 Atoms and the Periodic Table
The smallest piece of an element that maintains the identity of that element is called an atom.
The general tenets of Dalton’s atomic theory were as follows:
All matter is composed of extremely small particles called atoms
Atoms of a given element are identical in size, mass, and other properties. Atoms of different
elements differ in size, mass, and other properties.
Atoms cannot be subdivided, created, or destroyed
Atoms of different elements can combine in simple whole number ratios to form chemical
compounds
In chemical reactions, atoms are combined, separated, or rearranged
Atoms are composed of smaller parts called subatomic particles: electron (negative charge, 1 amu),
proton (positive charge) and neutron (neutral, 1 amu).
The relatively massive protons and neutrons are collected in the center of an atom, in a region called
the nucleus of the atom.
A useful unit to measure atomic mass is the atomic mass unit (amu), where 1 amu = 1.660539 x
10^-24 g
Week 1 Chemie 1
, The fundamental characteristic that all atoms of the same element share is the number of protons. This
number of protons is so important to the identity of an atom that it is called the atomic number (Z). The
number of protons in an atom is the atomic number of the element.
Atoms are electrically neutral, meaning that the overall electric charge is zero. This is because the
number of protons equals the number of electrons. Therefore, the atomic number also provides the
number of electrons. Atoms that have a charge are called ions.
Atomic number = Z = p+ = e- (by neutral charge)
The mass number (A) is defined as the total number of protons and neutrons in an atom:
Mass number = A = p+ + n
Atoms of the same element always have the same number of protons, same Z, but often have different
numbers of neutrons, therefore, different mass numbers. These atoms are called isotopes.
Isotopes are atoms of the same element that contain different numbers of neutrons. This difference in
neutron amount affects the mass number (A) but not the atomic number (Z). The figure below shows
an easy way to represent isotopes with a nuclear symbol.
Week 1 Chemie 2
