EL4 Organising The Elements Of Life Flashcards
How did Mendeleev arrange his periodic table?
In order of increasing relative atomic mass.
What did Henry Moseley discover?
Ordering the periodic table by atomic number was more accurate.
How does Mendeleev’s periodic table differ from the modern periodic table?
Some elements are out of atomic mass order in the modern periodic table.
What do elements in the same block share?
Similar properties.
What is periodicity?
The occurrence of periodic patterns.
What are intermolecular forces?
The bonds between the individual atoms or molecules.
What must be overcome when elements are melted or boiled?
The intermolecular forces.
What does it mean if an element has a high boiling and melting point?
It has strong intermolecular bonds.
What does it mean if an element has a low boiling and melting point?
It has weak intermolecular bonds.
What are the melting and boiling points a measure of?
The energy required to separate the particles in a substance.
What happens to the melting points across a period?
There is a general increase and then a decrease.
Why do the melting points increase in metals across a period?
Due to the increasing strength of metallic bonding caused by larger numbers of electrons contributing to the electron cloud.
Why does silicon have a high melting point?
It has a giant molecular structure, so a lot of energy is required to break the many covalent bonds.
What kind of molecules have much lower melting points?
Simple covalent molecules.
What are chemical properties of an element decided by?
The electrons in the incomplete outer shells.
