What is the approximate radius of an atom?
1x10-10 m
Atoms are very small.
Atoms consist of a positively charged nucleus containing ________ and ________.
protons and neutrons
The nucleus is surrounded by negatively charged electrons.
The radius of a nucleus is less than _______ of the radius of an atom.
1/10000
The mass of an atom is concentrated in the nucleus.
What is the atomic number?
Number of protons in an atom
All atoms of a particular element have the same number of protons.
The mass number of an element is the total number of _______ and _______.
protons and neutrons
It reflects the composition of the nucleus.
What are the relative charges of the subatomic particles: protons, electrons, and neutrons?
- Protons: +
- Electrons: -
- Neutrons: 0
This defines the basic electrical properties of these particles.
Electrons in an atom occupy the ________ available energy level.
lowest
This arrangement minimizes energy.
Atoms have no overall electrical charge because the number of electrons is equal to the number of _______.
protons
This balance maintains electrical neutrality.
Elements that react to form positive ions are called _______.
metals
Metals tend to lose electrons.
Isotopes are atoms of the same element that have different numbers of _______.
neutrons
This affects the atomic mass but not the chemical properties.
Before electrons were discovered, atoms were thought to be tiny spheres that could not be _______.
divided
This was the initial atomic theory.
The plum pudding model describes the atom as a ball of positive charge with negative electrons embedded throughout it. True or False?
TRUE
This model was proposed after the discovery of electrons.
The nuclear model concluded that the mass of an atom was concentrated in the _______.
nucleus
This model was developed after the alpha particle scattering experiment.
What is the arrangement of elements in the periodic table based on?
Increasing atomic number
Elements with similar properties are grouped in columns.
Elements in the same group have similar properties because they have the same number of _______.
electrons in their outer shell
This similarity affects their chemical behavior.
Elements in Group 0 are called the ________.
Noble Gases
They are unreactive due to a stable arrangement of electrons.
The Alkali metals are found in which group of the periodic table?
Group 1
They have 1 electron in their outer shell.
What happens to the reactivity of alkali metals as you go down the group?
Increases
This trend is due to the increasing distance of the outer electron from the nucleus.
Elements in Group 7 are known as the ________.
Halogens
They have 7 electrons in their outer shell.
What is the trend for melting and boiling points of halogens as you go down the group?
Increase
This is due to increasing relative molecular mass.
Many transition elements can form ions with ________ charges.
different
This property distinguishes them from Group 1 elements.
