Everything Science Grade 10

4.6 CHAPTER 4. THE ATOM

• Thestandard notationthat is used to write an element, isAZX, where X is the element
  symbol, A is the atomic mass number and Z is the atomic number.


• Theisotopeof a particular element is made up of atoms which have the same number
  of protons as the atoms in the original element, but a different number of neutrons.
  This means that not all atoms of an element will have the same atomic mass.


• Within each energy level, an electron may move within a particular shape oforbital.
  An orbital defines the space in which an electron is most likely to be found.


• Theelectron configurationis the arrangement of electrons in an atom, molecule or
  other physical structure.


• Energy diagrams such asAufbau diagramsare used to show the electron configura-
  tion of atoms.


• The electron configuration of an atom can be given using spectroscopic notation.


• Different orbitals have different shapes: s orbitals are spherically shaped and p or-
  bitals are dumbbell shaped.


• The electrons in the outermost energy level are calledvalence electrons.


• The electrons in an atom that are not valence electrons are calledcore electrons.


• Atoms whose outermost energy level is full, are less chemically reactive and therefore
  more stable, than those atoms whose outermost energy level is not full.

Chapter 4 End of chapter exercises

1. Write down only the word/term for each of the following descriptions.

a. The sum of the number of protons and neutrons in an atom

b. The defined space around an atom’s nucleus, where an electron is

most likely to be found

2. For each of the following, say whether the statement is true or false. If it

is false, re-write the statement correctly.

a.^2010 Ne and^2210 Ne each have 10 protons, 12 electrons and 12 neutrons.

b. The atomic mass of any atom of a particular element is always the

same.

c. It is safer to use helium gas rather than hydrogen gas in balloons.

d. Group 1 elements readily form negative ions.

3. The three basic components of an atom are:

a. protons, neutrons, and ions

b. protons, neutrons, and electrons

c. protons, neutrinos, and ions

d. protium, deuterium, and tritium

4. The charge of an atom is:

a. positive

92 Chemistry: Matter and Materials