Similar Questions
Atomic Number The atomic number (represented by the letter Z) of an element is the number of protons in the nucleus of each atom of that element. An atom can be classified as a particular element based solely on its atomic number. The single most important characteristic of an atom is its atomic number (usually denoted by the letter Z), which is defined as the number of units of positive charge (protons) in the nucleus. For example, if an atom has a Z of 6, it is carbon, while a Z of 92 corresponds to uranium. A neutral atom has an equal number of protons.
Chemistry
Which atom has the smallest valence p atomic orbital? -Carbon -Nitrogen -Sulfur Why? A. That atom has the highest electronegativity. B. That atom has the fewest number of electrons. C. That atom does not have electrons in pScience--HELP!!
Can you please check my answers: 1. Dalton's idea that atoms cannot be divided into smaller parts was disproved by the discovery of _________ (electrons?) 2. The description of the structure of the atom is called ______ (atomicCalculus help and please check answer for a)
The decay of a certain substance is modeled by the function N(t)=100(3+e^(-t/3), where the number of particles is represented by N in a time of t hours. a) what is the initial number of particles? - I set t as 0 and got an answerscience,
1. How many periods are there in the periodic table? * 1 point 6 7 8 9 2. How many groups are there in the periodic table? * 1 point 15 16 17 18 3. State the number of valence electrons in an atom of Sulfur. * 1 point 2 4 6 8 4.
Jan 24, 2021 The atomic number is the number of protons — positively charged particles — in the nucleus an atom of a chemical element. Elements are distinguished from one another by the numbers of these particles they have, and so each element has its own unique atomic number. Fundamental properties of atoms including atomic number and atomic mass. The atomic number is the number of protons in an atom, and isotopes have the same atomic number but differ in the number of neutrons. The atomic number (symbol: Z) of an atom is the number of protons in the nucleus of the atom. The atomic number of an atom identifies which element it is. In a neutral atom, the atomic number is equal to the number of electrons orbiting the nucleus. The elements of the periodic table are listed in order of increasing atomic number. Atomic number is not the same as.
- Atomic model
- Basic properties
- The electron
- The nucleus
- Development of atomic theory
- The beginnings of modern atomic theory
- Studies of the properties of atoms
- Models of atomic structure
- Advances in nuclear and subatomic physics
Please select which sections you would like to print:
While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions.
Our editors will review what you’ve submitted and determine whether to revise the article.
Join Britannica's Publishing Partner Program and our community of experts to gain a global audience for your work! ![The atomic number of an atom is what The atomic number of an atom is what](/uploads/1/1/8/9/118924977/748212760.jpg)
Articles from Britannica Encyclopedias for elementary and high school students.
George F. BertschSee All ContributorsProfessor of Physics, University of Washington, Seattle. Author of Oscillations in Finite Quantum Systems.
Atom, smallest unit into which matter can be divided without the release of electrically charged particles. It also is the smallest unit of matter that has the characteristic properties of a chemical element. As such, the atom is the basic building block of chemistry.
Most of the atom is empty space. The rest consists of a positively charged nucleus of protons and neutrons surrounded by a cloud of negatively charged electrons. The nucleus is small and dense compared with the electrons, which are the lightest charged particles in nature. Electrons are attracted to any positive charge by their electric force; in an atom, electric forces bind the electrons to the nucleus.
Because of the nature of quantum mechanics, no single image has been entirely satisfactory at visualizing the atom’s various characteristics, which thus forces physicists to use complementary pictures of the atom to explain different properties. In some respects, the electrons in an atom behave like particles orbiting the nucleus. In others, the electrons behave like waves frozen in position around the nucleus. Such wave patterns, called orbitals, describe the distribution of individual electrons. The behaviour of an atom is strongly influenced by these orbital properties, and its chemical properties are determined by orbital groupings known as shells.
This article opens with a broad overview of the fundamental properties of the atom and its constituent particles and forces. Following this overview is a historical survey of the most influential concepts about the atom that have been formulated through the centuries. For additional information pertaining to nuclear structure and elementary particles, seesubatomic particles.
Get a Britannica Premium subscription and gain access to exclusive content. Subscribe Now
Atomic model
The Atomic Number Of An Atom Is Equal To The Number Of
Most matter consists of an agglomeration of molecules, which can be separated relatively easily. Molecules, in turn, are composed of atoms joined by chemical bonds that are more difficult to break. Each individual atom consists of smaller particles—namely, electrons and nuclei. These particles are electrically charged, and the electric forces on the charge are responsible for holding the atom together. Attempts to separate these smaller constituent particles require ever-increasing amounts of energy and result in the creation of new subatomic particles, many of which are charged.
As noted in the introduction to this article, an atom consists largely of empty space. The nucleus is the positively charged centre of an atom and contains most of its mass. It is composed of protons, which have a positive charge, and neutrons, which have no charge. Protons, neutrons, and the electrons surrounding them are long-lived particles present in all ordinary, naturally occurring atoms. Other subatomic particles may be found in association with these three types of particles. They can be created only with the addition of enormous amounts of energy, however, and are very short-lived.
All atoms are roughly the same size, whether they have 3 or 90 electrons. Approximately 50 million atoms of solid matter lined up in a row would measure 1 cm (0.4 inch). A convenient unit of length for measuring atomic sizes is the angstrom (Å), defined as 10−10 metre. The radius of an atom measures 1–2 Å. Compared with the overall size of the atom, the nucleus is even more minute. It is in the same proportion to the atom as a marble is to a football field. In volume the nucleus takes up only 10−14 metres of the space in the atom—i.e., 1 part in 100,000. A convenient unit of length for measuring nuclear sizes is the femtometre (fm), which equals 10−15 metre. The diameter of a nucleus depends on the number of particles it contains and ranges from about 4 fm for a light nucleus such as carbon to 15 fm for a heavy nucleus such as lead. In spite of the small size of the nucleus, virtually all the mass of the atom is concentrated there. The protons are massive, positively charged particles, whereas the neutrons have no charge and are slightly more massive than the protons. The fact that nuclei can have anywhere from 1 to nearly 300 protons and neutrons accounts for their wide variation in mass. The lightest nucleus, that of hydrogen, is 1,836 times more massive than an electron, while heavy nuclei are nearly 500,000 times more massive.
Basic properties
Atomic number
The single most important characteristic of an atom is its atomic number (usually denoted by the letter Z), which is defined as the number of units of positive charge (protons) in the nucleus. For example, if an atom has a Z of 6, it is carbon, while a Z of 92 corresponds to uranium. A neutral atom has an equal number of protons and electrons so that the positive and negative charges exactly balance. Since it is the electrons that determine how one atom interacts with another, in the end it is the number of protons in the nucleus that determines the chemical properties of an atom.
Quick Facts
The Atomic Number Of An Atom Is Quizlet
- key people
- related topics