1.1 Atomic Structure Flashcards
What is the Mass number
Number of Protons + Neutrons
What is Atomic number, what is it also called?
Number of protons. Or number of electrons in a neutral atom of that element. Also called Proton Number.
What are subatomic particles, name them.
Particles that make up an atom. Electrons, Protons, Neutrons.
What are the relative masses and charges of the subatomic particles?
PROTON 1 AND +1
NEUTRON 1 AND
ELECTRON 1/1836 (NEGLIGIBLE) AND -1
How do the subatomic particles behave in an electric field and why.
Electrons deflected the most towards positive plate: small mass and negative charge
Protons: Deflected less than electrons towards negative plate: positive charge and larger mass
Neutrons: not deflected: neutral/ no charge
What is the mass number also called.
Nucleon number. Protons and neutrons are nucleons.
What holds an atom together?
Electrostatic force of attraction between positively charged nucleus and negatively charged electrons orbiting around it.
How do you calculate number of neutrons?
Mass number - atomic number
What is Atomic Radius?
It is half the distance between the two nuclei of two covalently bonded atoms of the same type.
What are the General trends for atomic radius, why?
- Atomic radii decrease as you move across a Period as the atomic number increases (increased positive nuclear charge) but at the same time extra electrons are added to the same principal quantum shell
The larger the nuclear charge, the greater the pull of the nuclei on the electrons which results in smaller atoms - Atomic radii increase moving down a Group as there is an increased number of shells going down the Group
The electrons in the inner shells repel the electrons in the outermost shells, shielding them from the positive nuclear charge
This weakens the pull of the nuclei on the electrons resulting in larger atoms - The diagram shows that the atomic radius increases sharply between the noble gas at the end of each period and the alkali metal at the beginning of the next period
This is because the alkali metals at the beginning of the next period have one extra principal quantum shell
This increases shielding of the outermost electrons and therefore increases the atomic radius
What are the General trends for ionic radius, why?
Ions with negative charges are formed by atoms accepting extra electrons while the nuclear charge remains the same
The outermost electrons are further away from the positively charged nucleus and are therefore held only weakly to the nucleus which increases the ionic radius
The greater the negative charge, the larger the ionic radius
Positively charged ions are formed by atoms losing electrons
The nuclear charge remains the same but there are now fewer electrons which undergo a greater electrostatic force of attraction to the nucleus which decreases the ionic radius
The greater the positive charger, the smaller the ionic radius
What is an Isotope?
Isotopes are atoms of the same element that contain the same number of protons and electrons but a different number of neutrons
What are the properties of an isotope and why?
Isotopes have similar chemical properties but different physical properties
Chemical properties
Isotopes of the same element display the same chemical characteristics
This is because they have the same number of electrons in their outer shells
Electrons take part in chemical reactions and therefore determine the chemistry of an atom
Physical properties
The only difference between isotopes is the number of neutrons
Since these are neutral subatomic particles, they only add mass to the atom
As a result of this, isotopes have different physical properties such as small differences in their mass and density
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