Topic 2: Atoms, elements and compounds Flashcards
What is an element?
A substance made of atoms with the same number of protons.
What is a compound?
Two or more elements chemically bonded in a fixed proportion.
What is a mixture?
Two or more substances not chemically bonded together.
What is the structure of an atom?
Central nucleus (protons and neutrons) surrounded by electrons in shells.
What is the relative mass and charge of a proton?
Mass = 1, Charge = +1
What is the relative mass and charge of a neutron?
Mass = 1, Charge = 0
What is the relative mass and charge of an electron?
Mass ≈ 0, Charge = -1
What is the proton number (atomic number)?
Number of protons in an atom’s nucleus.
What is the nucleon number (mass number)?
Total number of protons and neutrons.
How to find the number of neutrons?
Mass number – proton number
How many electrons fit in the first shell?
2
How many electrons fit in the second shell?
8
What does the group number tell you?
The number of outer-shell electrons.
What does the period number tell you?
The number of occupied electron shells.
What is special about Group VIII (noble gases)?
They have a full outer shell.
What is an isotope?
Atoms of the same element with the same protons but different neutrons.
Why do isotopes have the same chemical properties?
They have the same number of electrons.
How do you write the symbol for an atom?
Example:
12
C
6
What changes between isotopes?
The mass number.
What is a cation?
A positive ion.
What is an anion?
A negative ion.
What is an ionic bond?
A strong electrostatic attraction between oppositely charged ions.
How do Group I and Group VII elements form ionic bonds?
Group I loses 1 electron; Group VII gains 1 electron.
What is the structure of an ionic compound?
A giant lattice of alternating positive and negative ions.
