Chapter 2 Flashcards
(27 cards)
What is an element?
A substance made up of just one type of atom is called an element.
What does the symbol ‘He’ represent?
He represents Helium.
What is a characteristic of an element?
Contains only one kind of atom.
What is a compound?
A substance formed by the chemical combination of two or more elements in fixed proportions.
What is the definition of an element in terms of protons?
A substance that cannot be further divided into simpler substances by chemical methods; all the atoms of an element contain the same number of protons.
How many known elements are there?
There are now 118 known elements.
How many elements are found naturally on Earth?
94 elements are found naturally on Earth.
What is an example of a common chemical compound?
Water (H2O)
Water is formed by the chemical combination of hydrogen and oxygen.
What are some examples of elements?
Helium (He), Oxygen (O), Sulphur, Carbon.
What is the chemical formula for Ammonia?
NH3.
What are the relative masses of a proton, neutron and electron?
A proton has a mass of 1, a neutron has a mass of 1, and an electron has a mass of approximately 1/1840.
How many protons, neutrons and electrons are there in an atom of phosphorus?
An atom of phosphorus has 15 protons, 16 neutrons, and 15 electrons.
What is the definition of an element?
An element is a substance that cannot be broken down into anything simpler by chemical means.
What is an atom?
Atoms are the particles that make up all substances; they are the smallest particle of an element that shows the properties of that element.
What is the relationship between atoms and elements?
Each element has its own type of atom, and the atoms of an element all have the same number of protons and electrons.
Why are neutrons important in making the nucleus of an atom stable?
Neutrons counteract the repulsion between positively charged protons, allowing the nucleus to hold together.
What is the mass number (A) of an atom?
Mass number (A) is the sum of the number of protons (Z) and the number of neutrons (N).
What is the atomic number?
The atomic number is the number of protons in an atom.
What is the relationship between protons and electrons in an atom?
In an atom, the number of protons equals the number of electrons.
What are the first 5 elements and their symbols?
- Hydrogen (H), 2. Helium (He), 3. Lithium (Li), 4. Beryllium (Be), 5. Boron (B).
What are the next 5 elements and their symbols?
- Sodium (Na), 7. Magnesium (Mg), 8. Aluminium (Al), 9. Silicon (Si), 10. Phosphorus (P).
What is a common chemical compound?
Water (H₂O)
Example: Water is formed from hydrogen and oxygen.
