science Flashcards
(31 cards)
What is the simplest form of matter that can exist on its own?
Atoms
Atoms are the fundamental building blocks of matter.
What are substances made up of only one type of atom called?
Elements
Elements cannot be broken down into simpler substances.
What are molecules made up of?
Two or more atoms joined together by chemical bonds
Molecules can be of the same or different elements.
What are compounds?
Molecules made up of two or more types of atoms joined together
Compounds have distinct properties different from their constituent elements.
What are the three subatomic particles in an atom?
Protons, neutrons, and electrons
These particles have distinct charges and masses.
What charge do protons have?
Positively charged
Protons are located in the nucleus of the atom.
What is the charge of neutrons?
Neutral (zero charge)
Neutrons are also found in the nucleus.
What is the charge of electrons?
Negatively charged
Electrons orbit the nucleus in shells.
In a neutral atom, what does the atomic number represent?
The number of protons
The atomic number also equals the number of electrons in a neutral atom.
What is the mass number of an atom?
The number of protons plus the number of neutrons
It reflects the total mass of the atom.
How do you find the number of neutrons in an atom?
Mass number - atomic number
This calculation gives the number of neutrons.
What is electron configuration?
The arrangement of electrons around an atom
This arrangement determines the chemical properties of the element.
What is the maximum number of electrons the first shell can hold?
2 electrons
The formula for maximum electrons in a shell is 2n².
What is the maximum number of electrons in the second shell?
8 electrons
The second shell can hold more electrons than the first.
What are valence electrons?
The number of electrons in the outermost shell
Valence electrons are crucial for chemical bonding.
What are isotopes?
Atoms of the same element with different mass numbers
Isotopes have the same number of protons but different numbers of neutrons.
How do you denote an isotope?
Element name followed by a hyphen and the mass number
Example: Sodium-23.
What is a radioisotope?
An unstable isotope that can spontaneously change and emit radiation
Radioisotopes can undergo radioactive decay.
What are the three types of radiation emitted by a radioisotope?
Alpha (α), beta (β), and gamma (γ)
These are known as ionizing radiation.
What is the periodic table?
An organized array of all chemical elements in order of increasing atomic number
The periodic table provides a systematic way to understand elements.
What are the horizontal rows in a periodic table called?
Periods
Each period represents elements with the same number of electron shells.
What are the vertical columns in a periodic table called?
Groups
Elements in the same group often have similar chemical properties.
What is metallic bonding?
A lattice of positive cations with a ‘sea’ of free delocalized electrons
This bonding accounts for many properties of metals.
List properties of metals
- Malleable
- Ductile
- Lustrous
- Conduct heat and electricity
- Solid at room temperature (except Mercury)
- Hard and dense
- Tensile strength
These properties make metals useful in various applications.
