atoms and molecules Flashcards
definition of atoms.
Atoms are the simplest unit of an element. Atoms cannot be broken down into simpler substances. IT cannot be seen with a naked eye, it is microscopic.
Differences between atoms and molecules
Molecules are made up of 2 or more atoms that are combined while atoms are the simplest unit of element that can exist, it cannot be seen with a naked eye
What is the number located on the top of an element in the periodic table?
The number on the top of the periodic table is called the proton number also known as the atomic number. The proton number always equals to the number of electrons.
What is a molecule of an element?
A molecule of an element contains one type of atom which is a fixed number
what is the number located on the bottom of the element?
It is the called the mass or nucleon number. The weight of the atom depends on the nucleon or mass number. the nucleon/mass number is made up of the sum of protons and neutrons
What are isotopies?
Isotopies are atoms from the same element which consists of the same number of protons but different numbers of neutrons. An example would be 75% of chlorine gas consists of chlorine-35 while 25% of chlorine gas consists of Chlorine-37
What are some disadvantages of isotopies?
Isotopies that emit high-energy radiation are called radioisotopes which emits dangerous radiation that can cause damage to living cells which causes cancer.
What are some advantages of isotopies?
Radioisotopes are used in smoke detectors. Smoke entering the smoke detectors absorbs the radiation which causes the alarm to set off.
What is the valence shell?
The valence cell is the outer cell that is furthest away from the nucleus. It has the most energy and can hold up to 8 electrons
What is the properties of the first shell?
The first shell is the closet to nucleus it has the lowest energy and is always filled up the first. However, it can only hold up to 2 electrons maximum
Why is the chemical formula useful?
The chemical formula allows us to see teh different symbols of each element and the number of toms in each element
What are molecules?
Molecules are made up two or more atoms combined together
Definition if molecules of compounds
molecules of compound are made up a fixed number of two or more different types of atoms combined
Definition of molecule of elements?
Molecules of elements are made up of a fixed number of the same type of atoms
