Chem Chapter 4
Terms
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- An atom is the
- smallest particle of an element that retains the properties of that element.
- Electrons are
- negatively charged subatomic particles.
- A proton is
- a positively charged subatomic particle.
- A neutron is a
- subatomic particle with no charge, but their mass nearly equals that of the proton.
- The nucleus is the
- central core of an atom, composed of protons and neutrons.
- The atomic number of an element is the number of protons in the
- nucleus of the atoms of that element.
- The mass number of an atom is
- the total number of protons and neutrons in the nucleus.
- ⬢ Atoms that have the same number of protons but different numbers of neutrons are called
- isotopes.
- An atomic mass unit (amu) is defined as
- one-twelfth the mass of a carbon-12 atom.
- The atomic mass of an element is
- a weighted average mass of the atoms in a naturally occurring sample of the element.