Atoms, elements and compounds Flashcards
What is the mass and charge of a proton?
Mass: 1 unit
Charge: +1
What is the mass and charge of a neutron?
Mass: 1 unit
Charge: no charge
What is the charge of an electron?
Charge: -1
What is the proton number/atomic number?
number of protons in nucleus of atom
What is the nucleon number?
number of protons and neutrons in the nucleus of an atom/relative atomic mass
What do columns in a periodic table show?
groups with similar reaction properties
What do rows in a periodic table show?
periods
What are isotopes?
atoms of same element with same proton number, different number of neutrons → different nucleon number
Why do isotopes have the same properties?
same properties because same number of electrons in outer shell
What are the two types of isotopes?
radioactive
non-radioactive
What are some medical and industrial uses for radioactive isotopes?
Medical: cancer treatment, locating tumours
Industrial: check for oil and gas leaks
What is oxidation state/valency number?
number of electrons in outer shell
Why is group 0 unreactive?
full outershell
Why do atoms with more electron shells have higher energy levels?
Further away from nucleus
What is an ion?
electrically charged particle
What is an ionic bond made of?
Metals + Non-metals
How are ionic bonds formed?
Atoms lose/gains electrons to become stable
What is the structure of ionic bonds?
arranged in a giant lattice with regular pattern of particles held together by strong ionic bonds
What are the properties of ionic compounds (5)?
High boiling + melting points (ionic bonds strong)
Poor conductors as solid (no free electrons/ions)
Conducts electricity as liquid
Hard
Soluble in water
Why do ionic compounds have high fixed points?
ionic bonds strong, lots of energy required to overcome electrostatic attraction
Why do ionic compounds conduct electricity as liquid?
charged ions free to move
What is a covalent bond made of?
Non-metal + Non-metal
What are molecules?
a group of atoms held together by COVALENT bonds
How are covalent bonds formed?
Atoms share pairs of electrons to achieve noble gas configuration
What is the strength of bonding in covalent bonds ?
Molecular bonds strong, intermolecular are weak
What are the properties of covalent compounds?
Low melting/boiling points
Don’t conduct electricity (not charged)
Insoluble in water, but dissolve in organic solvents
Why do covalent compounds have low fixed points?
weak intermolecular forces
How many electrons are shared in a single, double and triple covalent bond?
Single bond: 2 electrons shared (1 from each atom)
Double bond: 4 electrons shared (2 from each atom)
Triple bond: 6 electrons shared (3 from each atom)
Why do giant covalent structures have high fixed points?
structure made up of strong covalent bonds
Why don’t giant covalent structures conduct electricity?
have no mobile ions or electrons, except for graphite
What are the properties of diamond? (4)
Shares 4 valence electrons → 3D lattice
Strong covalent bonds
High fixed points
Forms tetrahedron
What are the properties of graphite? (6)
Shares 3 valence electrons
4th electron free – Free moving electrons
Strong covalent bonds
Held together by weak forces so is soft and slippery -used as a lubricant
Slide over each other
What are the properties of silicon dioxide? (5)
Makes up sand Each Si is bonded to 4 oxygen atoms Each oxygen bonded to 2 silicon atoms High fixed points Hard
What are delocalized electrons
Free electrons in metallic bonding
Why can metals conduct electricity and heat?
Delocalized electrons can carry charge
Why are metals malleable + ductile?
attractive forces between metal ions and electrons act in any direction – when layers slide new bonds can easily form
