2.1 Elements and Atoms: The Building Blocks of Matter

Fill-in-the-blank flashcards covering key concepts from the OpenStax 2.1 Elements and Atoms section.

Matter is defined as anything that occupies space and has __.

mass

An object's weight is its mass as affected by __.

gravity

An element is a pure substance that cannot be created or broken down by __ chemical means.

ordinary

Calcium (Ca) is essential to the human body and is absorbed and used for processes, including strengthening __.

bones

The elements in the human body are primarily oxygen, carbon, hydrogen, and __.

nitrogen

An atom is the smallest quantity of an __ that retains the unique properties of that element.

element

Protons are positively charged, electrons are negatively charged, and neutrons are __.

neutral

The atomic number is the number of __ in the nucleus.

protons

An element's mass number is the sum of the number of protons and __ in its nucleus.

neutrons

The most common form of carbon has six protons and six neutrons, for a mass number of __.

12

Uranium (U) has an atomic number of 92 and a mass number of __.

238

The periodic table is organized by atomic __; hydrogen and helium are at the top.

number

Isotopes differ from one another by having different numbers of __.

neutrons

A radioactive isotope is one whose nucleus readily decays, giving off subatomic particles and electromagnetic energy; different isotopes differ in their __.

half-life

The first electron shell can hold up to __ electrons.

2

All atoms are most stable when there are exactly eight electrons in their valence shell; this is known as the __ rule.

octet

In water (H₂O), oxygen commonly interacts with two hydrogen atoms, forming __ bonds.

covalent

The number of electrons in an atom's outermost shell is the atom's __ electrons.

valence

The atomic number identifies the __ of the element.

element

Isotopes can be indicated with the mass number hyphenated (for example, C-12) as a form of __ notation.

isotope

Heavy isotopes tend to be __ and radioactive.

unstable

Radioisotopes emit subatomic particles that can be detected by imaging technologies; the PET scanner detects radioactive __ in tissues.

glucose

The first electron shell can hold only __ electrons.

2

Hydrogen and helium are the only elements with just one electron __; they sit at the sides of the top row.

shell

The octet rule states that atoms are most stable when there are eight electrons in their __ shell.

valence

Oxygen commonly interacts with two hydrogen atoms to form __.

water

The name 'hydrogen' reflects its contribution to water; hydro- means 'water' and -gen means __.

maker