Physical Science Cycle Test 16/04/24 Flashcards
To prepare for my cycle test
Chemical Bonds
These are attractive forces between the nucleus of an and its own electrons.
Covalent Bonds
The sharing of at least one pair of electrons by two non-metal atoms.
TRUE or FALSE: The sharing of the electrons with same spin then occurs when two half-filled orbitals overlap to form a new filled orbital.
FALSE. The sharing of the electrons with (opposite) spin then occurs when two half-filled orbitals overlap to form a new filled orbital.
TRUE or FALSE: Covalent bonds have the lowest melting and boiling points, as the forces of attraction between atoms are weaker if the bonds between are covalent.
TRUE. Covalent bonds DO have the lowest melting and boiling points, as the forces of attraction between atoms are weaker if the bonds between are covalent.
TRUE or FALSE: Noble gases do not bond with other elements, except with each other.
FALSE. Noble gases do not bond with other elements (and maybe not each other).
Lewis notation and structures ( or electron-dot structures)
We can use Lewis notation to represent atoms and core electrons (chemical symbol) and their valence electrons (dots and crosses).
Chemical bonds types
- Covalent bonds
- Ionic bonds
- Metallic bonds
Dipole
If one positive charges and one negative charges are separated, a small distance is formed.
Polar covalent bond
When two atoms bond together but share the electron pair unequally and a small dipole is formed.
Non-polar covalent bond
When two atoms bond together and share the electron pair equally, then no dipole will be formed. One atom will not be more negative and the other more positive.
Electronegativity
Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. Atoms with a strong attraction to the shared electrons in a bond have high electronegativity, and atoms with a weak attraction have low electronegativity.
TRUE or FALSE: Polar covalent bonds have one atom with high electronegativity and one with low electronegativity, thus the shared electron pair will be unequal. One atom will be more negative and the other more positive.
TRUE. Polar covalent bonds have one atom with high electronegativity and one with low electronegativity, thus the shared electron pair will be unequal. One atom will be more negative and the other more positive.
TRUE or FALSE: For non-polar covalent bonds, each will have the same electronegativity and therefore the difference between the each ones electronegativity is zero. The attraction to the shared paired of electrons is the same for one of the atoms.
FALSE. The attraction to the shared paired of electrons is NOT the same for one of the atoms but both of the atoms.
Ionic Bonds
This occurs between atoms where the difference in electronegativity is so large that no sharing, or very little sharing, of electrons between the atoms occurs. Instead, electrons are transferred from one atom to the other atom.
An ionic bond generally forms between a metal (or ammonium) ion and a non-metal (or polyatomic) ion.
It is a transfer of electrons and subsequent electrostatic attraction.
Properties of Ionic substances
- high melting and boiling points, which is a result of the strong attractive forces between the ions
- cannot conduct electricity in the solid phase because they do not have ions that can move, to act as carriers of electricity
Metallic bonds
A bond between a positive kernel and a sea of delocalised electrons.
TRUE or FALSE: To form a metallic bond, the atoms must have low ionisation energy. The valence electrons must be able to be loosened easily. The atoms must also have empty valence orbitals for more movement space.
TRUE.
Properties of Metallic Substances
Metals are good conductors of electricity. Metals are also malleable because the atoms can glide across each other when the piece of metal is deformed.
Atoms
Atoms are the very small particles of which all substances are made.
Elements
Elements are substances that contain only one kind of atom.