science term 1 2024 Flashcards
A heterogenous mixture is…?
a mixture that is NOT evenly distributed
a homogenous mixture is…?
a mixture that IS evenly distributed
Explain the difference between an element and a compound.
An element is a substance made up of only one type of atom, while a compound is a substance made up of two or more different types of atoms chemically bonded together.
How are elements organized on the periodic table?
Elements are organized on the periodic table based on their atomic number and chemical properties. They are arranged in rows (periods) and columns (groups) according to similar properties.
(True or False) Compounds can be separated into their constituent elements by physical means
False
(True or False)
The chemical formula for water is H₃O.
False
(True or false)
Elements can combine in different ratios to form different compounds
True
(True or False)
All substances are either elements or compounds
False
Which of the following is an example of a compound?
a) Oxygen (O)
b) Hydrogen (H)
c) Water (H₂O)
- c) Water (H₂O)
How are elements represented on the periodic table?
a) By their chemical formula.
b) By their atomic number and symbol.
c) By their molecular structure.
b) By their atomic number and symbol.
The smallest particle of an element is called a ________.
atom
A chemical bond is a force that holds ________ together.
atoms
A substance made up of two or more elements chemically combined in a fixed ratio is called a ________.
compound
The chemical formula for table salt (sodium chloride) is ________
NaCl
Describe John Dalton’s atomic theory and its key principles.
John Dalton’s atomic theory proposed that atoms are indivisible and indestructible particles. It also suggested that atoms of different elements are different and that chemical reactions involve the rearrangement of atoms.
Explain the major contributions of Niels Bohr to the atomic model
Niels Bohr’s major contribution was the proposal of a model where electrons orbit the nucleus in fixed energy levels or shells. He also introduced the idea that electrons can jump between these energy levels by absorbing or emitting energy.
How did the discovery of the electron impact the understanding of the atom?
The discovery of the electron by J.J. Thomson led to the understanding that atoms are not indivisible as proposed by Dalton but are composed of smaller particles. This discovery paved the way for further exploration of atomic structure.
The ________ model proposed that atoms are made up of a positively charged nucleus surrounded by negatively charged electrons.
bohr
In Rutherford’s gold foil experiment, most alpha particles passed through the foil, indicating that atoms are mostly ________.
empty space
The modern atomic model describes the atom as a nucleus composed of protons and ________ surrounded by orbiting electrons.
neutrons
is a proton
-negatively charged
-positively charged
-neutrally charged
positively charged
is an electron
-negatively charged
-positively charged
-neutrally charged
negatively charged
is a neutron
-negatively charged
-positively charged
-neutrally charged
neutrally charged
The ancient Greeks proposed the concept of the atom as the smallest indivisible particle.
(True/False)
true