The Atom

Question 1

Atoms are

Answer 1

the ‘building blocks’ of all substances
atoms cannot
be split chemically into anything smaller
the smallest particles

Question 2

molecules are

Answer 2

atoms chemically bounded together

Question 3

elements…..

Answer 3

contain only one sort of atom, alone or grouped into molecules, but only one type of atom

Question 4

compounds…..

Answer 4

contain more than one type of atom from one type of molecule

Question 5

mixtures

Answer 5

contain more than one type of molecule

Question 6

describe an atom

Answer 6

the smallest particles and consists of
A Nucleus containing Protons + and Neutrons no charge.
Electrons - charge, surround the nucleus
Electrons are arranged in energy levels or shells
Number of Protons is the atomic number

Question 7

What is the atomic number

Answer 7

the number of Protons ( contained in the Nucleus )

Question 8

What are Ions

Answer 8

The number of electrons in an atom is always the same as the number of protons, so atoms are electrically neutral overall. Atoms can lose or gain electrons. When they do, they form charged particles called ions:
if an atom loses one or more electrons, it becomes a positively charged ion
if an atom gains one or more electrons, it becomes a negatively charged ion

Question 9

How are electrons arranged in an atom

Answer 9

Electrons are arranged in different shells around the nucleus. The innermost shell - or lowest energy level - is filled first. Each succeeding shell can only hold a certain number of electrons before it becomes full. The innermost shell can hold a maximum of two electrons, the second shell a maximum of eight, and so on.

Question 10

what is reactivity

Answer 10

the relative capacity of an atom to undergo a chemical reaction with another atom, .

as atoms become larger and the outer electron is further from the nucleus. The force of attraction between the positively-charged nucleus and the negatively-charged outer electron becomes weaker, which is why the outer electron is more easily lost

Question 11

The atomic mass number is

Answer 11

the total number of protons and neutrons in an atom.

Question 12

Carbon chemical symbol is

6

what does this tell us

Answer 12

The full chemical symbol for an element shows its mass number at the top and atomic number at the bottom

It tells us that a carbon atom has:

Six protons (because its proton number, at the bottom, is 6)
Six electrons (because the number of protons and electrons in an atom is the same)
The symbol also tells us that the total number of protons and neutrons in a carbon atom is 12.

Question 13

what is an isotope

Answer 13

An isotope has the same number of protons, but a different number of neutrons

Question 14

What is molecular mass

Answer 14

molecular mass is the mass of
one molecule of the substance compared to the
mass of one atom of hydrogen

Question 15

electron shell configuration has an effect on reactivity

Describe non reactive element giving 3 examples

Answer 15

The elements having a completely filled outermost orbit (or shell) will be chemically inert (non-reactive). For example, the outermost shell in the case of helium (He), neon (Ne) and argon (Ar) are completely filled as shown below. As a result, helium, neon, and argon are chemically inactive (or inert). These elements do not form compounds with other elements.

Because of this chemical inactivity, these gases are called as noble gases

Question 16

electron shell configuration has an effect on reactivity

describe a reactive element

give 2 examples

Answer 16

The elements containing only one or seven electrons in their outermost shell show greater chemical reactivity, i.e., such elements react very fast with other elements. For examples, sodium and chlorine having the follows electronic configurations are highly reactive.

Sodium 2, 8, 1 —- Here, the outermost shell has been one one electron: one more than the completely filled shell.

Chlorine 2, 8, 7 —– Here, the outermost shell has seven electrons: one less than that required to fill the shell completely.