Atoms and Compounds

Question 1

How are all atoms electrically neutral

Answer 1

This is because they have the same number of positively charged particles (protons) as negatively charged particles (electrons)

Question 2

What is the atomic number

Answer 2

• The atomic number of an atom is the number of protons in the atom.
• This is also the number of electrons in a neutral atom since the number of protons is equal to the number of electrons. Opposite charges cancel each other out leaving the atom neutral.

Question 3

Why do elements in a group show similar chemical properties

Answer 3

-Same amount of electrons

Question 4

What is the mass of an atom

Answer 4

-Effectively the mass of an atom is the mass of its protons and
neutrons.

Question 5

What are isotopes

Answer 5

• Isotopes are atoms of the same element with a different number of neutrons and, therefore, a different mass.
• Isotopes must have the same number of protons since they are atoms of the same element.

Question 6

What is relative atomic mass (R.A.M)

Answer 6

-The average of the masses of all the isotopes of an element.
Most elements exist as a mixture of isotopes.
To calculate the relative atomic mass of an element you need the relative abundance (%) of each isotope.
Calculate the percentage of each isotopes mass. With chlorine, for example:
25% of 37 + 75% of 35
= 9.25 + 26.25

Question 7

What are ions.

Answer 7

• When atoms are not neutral they are called ions.
• Ions are formed when atoms lose or gain electrons.
• Atoms lose or gain electrons to become more stable.
• Atoms are at their most stable when they have a full outer energy level.

Question 8

Why do atoms want to have a full outer shell?

Answer 8

Atoms are at their most stable

Question 9

Metal and non-metal atoms (ions)

Answer 9

Metal atoms always lose electrons to become positive ions. This is because most metals have 1, 2 or 3 electrons in their outer energy level. It is easier to lose 1, 2 or 3 electrons than to gain 5,6 or 7.

Non-metal atoms always gain electrons to become negative ions. This is because most non-metals that form ions have 5, 6 or 7 electrons in their outer energy level. It is easier to gain 1, 2 or 3 electrons than lose 5, 6 or 7.

Question 10

Ions description forming

Answer 10

• An atom can only lose an electron if another atom is present which can gain the electron from .
• Generally ions are only present in compounds.
• The ions are held together in the compound by the attraction of opposite charges.

Question 11

Compound naming

Answer 11

• Compounds are named in a special way.
• Compounds containing only two elements have their names ending with -ide.
• Compounds containing more than two elements, one of which is oxygen, the name of the compound ends with -ate or -ite.

Question 12

Prefixes to know

Answer 12

Mono- One
Di- Two
Tri- Three
Tetra- Four

Question 13

Ionic Compounds

Answer 13

• When a metal element chemically joins with a non metal element they form an ionic compound.
• An atom with ionic bonds is called an ionic compound

Question 14

Covalent Compounds

Answer 14

When two non metal elements chemically join they form a covalent compound.

Question 15

Definitions of Molecule and Molecular formula

Answer 15

Molecule – a group of two or more non-metal atoms joined together by covalent bonds.

Molecular formula gives the number of atoms of each element in a molecule.

Question 16

What’s the test for hydrogen

Answer 16

• It burns with a squeaky pop

Question 17

What are the Diatomic Elements

Answer 17

H NOF DOWN

Question 18

What is valency’s

Answer 18

The number that can be used up to write a chemical formula.