Everything Science Grade 10

4.6 CHAPTER 4. THE ATOM

1s

2s

2p

FACT

When we draw the
orbitals we draw
a shape that has
a boundary (i.e.
a closed shape).
This represents the
distance from the
nucleus in which
we are 95% sure
that we will find the
electrons. In reality
the electrons of an
atom could be found
any distance away
from the nucleus.

Orbital shapes ESABJ

Each of the orbitals has a different shape. The s orbitals are spherical and the p orbitals are

dumbbell shaped.

Figure 4.12: The orbital shapes. From left to right: an s orbital, a p orbital, the three p

orbitals

Core and valence electrons ESABK

Electrons in the outermost energy level of an atom are calledvalence electrons. The

electrons that are in the energy shells closer to the nucleus are calledcore electrons. Core

electrons are all the electrons in an atom, excluding the valence electrons. An element that

has its valence energy level full ismore stableandless likely to reactthan other elements

with a valence energy level that is not full.

86 Chemistry: Matter and Materials