Atoms & Chemical Bonds Flashcards
What were the four things proposed in Dalton’s Atomic Theory?
- All matter is made of atoms.
- All atoms of a given element are identical in mass and properties.
- Compounds are a combination of two or more different kinds of atoms.
- A chemical reaction is a rearrangement of atoms.
What is a molecule?
An electrically neutral group of two or more atoms held together by covalent chemical bonds.
What is a compound?
A pure substance made up of two or more elements in a fixed ratio by mass.
Where are protons, neutrons and electrons found in an atom?
Protons and neutrons - in the nucleus
Electrons - in a cloud outside the nucleus
What makes up a mass number?
Protons + Neutrons
What makes up an atomic number?
Protons
What makes up an atomic weight?
The weight of all sub-atomic particles.
What is an isotope?
An isotope is a version of an element with the same number of protons but different numbers of neutrons.
True or False: if an element has the same number of protons but different numbers of neutrons, it is the same element.
True, this is called and Isotope.
What is electron configuration?
The arrangement of electrons in the extranuclear space.
What does it mean when it is said that the energy of electrons in an atom is quantized?
It means that an electron is an atom can have only certain allowed energies.
What is ground-state electron configuration?
The electron configuration of the lowest energy state of an atom.
How many electrons does each shell hold?
1st shell - 2 electrons
2nd shell - 8 electrons
3rd shell - 18 electrons
4th shell - 32 electrons
True or False: movement between shell levels is possible with the addition or release of energy.
True.
How are orbitals filled?
Orbitals fill in the order of increasing energy from lowest to highest.
In what order are orbitals initially filled?
1s, 2s, 2p, 3s & 3p
True or False: each orbital can hold up to two electrons with spins paired.
True.
What happens when there are a set of orbitals with equal energy?
Each orbital becomes half filled before any of them become completely filled.
What do the boxes and arrows in orbital box diagrams represent?
Box - represents an orbital
Arrow - represents an electron
What do a pair of arrows with heads in opposite directions in an orbital box diagram represent?
It represents a pair of electrons with paired spins.
How is a covalent bond formed?
It is formed by the sharing of one or more pairs of electrons.
What are the four main biomolecules that make up animals?
Oxygen, Hydrogen, Carbon and Nitrogen
True or False: covalent bonds are strong.
True
